0001656423-24-000007 | 10-K | XBRL Viewer

Common stock, shares issued | shares

$ 500,000

$ 0

$ 1,841,500

157,019,766

156,836,767

Proceeds from Secured Notes Payable

$ 600,000

$ 0

$ 1,201,388

3 Hudson Boulevard [Member] | Unconsolidated Properties

25.00%

$ 80,000

3 Hudson Boulevard [Member] | Unconsolidated Properties | Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate

3.50%

7750 Wisconsin Avenue [Member] | Unconsolidated Properties

3.61%

50.00%

736,000

7750 Wisconsin Avenue [Member] | Unconsolidated Properties | Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate

1.25%

Construction Loan

$ 252,600

Restricted Stock [Member]

1.35%

Common stock, shares issued | shares

73,762

41,818

57,383

Proceeds from Secured Notes Payable

$ 500,000

$ 0

$ 1,841,500

$ 600,000

$ 0

$ 1,201,388

Boston Properties Limited Partnership | MYLTIP 2021

Number of shares issued | shares

352,021

Boston Properties Limited Partnership | LTIP Units [Member]

Number of shares issued | shares

430,824

280,616

281,640

Senior Notes | Boston Properties Limited Partnership

$ 10,550,000

Mortgages [Member]

3.916% unsecured senior notes | Senior Notes | Boston Properties Limited Partnership

$ 4,200,000

^[1]

3.80%

Subsequent Event [Member] | 3 Hudson Boulevard [Member] | Extended Maturity

^[1]

$ 700,000

Debt Instrument, Maturity Date

May 09, 2024

Subsequent Event [Member] | 3 Hudson Boulevard [Member] | Unconsolidated Properties

25.00%

Subsequent Event [Member] | 3 Hudson Boulevard [Member] | Unconsolidated Properties | Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate

$ 80,000

Subsequent Event [Member] | 7750 Wisconsin Avenue [Member] | Extended Maturity

3.61%

Debt Instrument, Maturity Date

Apr. 26, 2025

Subsequent Event [Member] | 7750 Wisconsin Avenue [Member] | Unconsolidated Properties

50.00%

736,000

Subsequent Event [Member] | 7750 Wisconsin Avenue [Member] | Unconsolidated Properties | Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate

$ 251,600

Construction Loan

$ 252,600

Subsequent Event [Member] | 901 New York Avenue

1.35%

$ 10,000

Subsequent Event [Member] | 901 New York Avenue | Joint Venture Partner [Member]

548,000

Subsequent Event [Member] | MYLTIP 2021

50.00%

Final awards percentage of target

112.00%

Value of MYLTIP Awards

$ 12,600

Forfeitures, in units | shares

155,625

Subsequent Event [Member] | Restricted Stock [Member]

Common stock, shares issued | shares

71,124

Subsequent Event [Member] | MYLTIP 2024

Share-based Compensation Arrangement by Share-based Payment Award, Terms of Award

The 2024 MYLTIP awards consists of three components. Two of the components, each weighted 40%, utilize BXP’s TSR over a three year measurement period as the performance metrics and the third component utilizes a leverage ratio as the performance metric.

Value of MYLTIP Awards

$ 11,100

Subsequent Event [Member] | Boston Properties Limited Partnership | LTIP Units [Member]

Number of shares issued | shares

429,237

Subsequent Event [Member] | Boston Properties Limited Partnership | MYLTIP 2024 | Minimum [Member]

Common stock available for issuance | shares

Subsequent Event [Member] | Boston Properties Limited Partnership | MYLTIP 2024 | Maximum [Member]

Common stock available for issuance | shares

330,479

Subsequent Event [Member] | Boston Properties Limited Partnership | MYLTIP 2024 | Target

Common stock available for issuance | shares

165,240

Subsequent Event [Member] | Mortgages [Member] | 901 New York Avenue

$ 207,100

3.61%

Subsequent Event [Member] | 3.916% unsecured senior notes | Senior Notes | Boston Properties Limited Partnership

3.80%

$ 700,000

Debt Instrument, Increase, Accrued Interest

713,300

$ 13,300

[1]	See Note 17.

Real Estate Amortization of Finite Lived Intangible Assets by Major Class (Details) $ in Thousands	Dec. 31, 2023 USD ($)
Acquired Finite-Lived Intangible Assets [Line Items]
2024	$ 52,489
2025	40,739
2026	27,095
2027	20,823
2028	11,113
Above Market Lease Intangibles [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
2024	3,985
2025	1,880
2026	982
2027	743
2028	605
Below Market Lease [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
2024	9,961
2025	9,756
2026	8,602
2027	5,432
2028	2,125
Santa Monica Business Park [Member] \| In-Place Lease Intangibles
Acquired Finite-Lived Intangible Assets [Line Items]
2024	32,362
2025	20,782
2026	7,986
2027	4,078
2028	2,726
Santa Monica Business Park [Member] \| Above Market Lease Intangibles [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
2024	3,584
2025	1,491
2026	593
2027	354
2028	216
Santa Monica Business Park [Member] \| Below Market Lease [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
2024	1,109
2025	944
2026	910
2027	910
2028	553
Santa Monica Business Park [Member] \| Ground Lease
Acquired Finite-Lived Intangible Assets [Line Items]
2024	10,979
2025	10,979
2026	10,979
2027	10,979
2028	$ 2,193

Summary Of Significant Accounting Policies

12 Months Ended

Dec. 31, 2023

Accounting Policies [Abstract]

Summary Of Significant Accounting Policies

2. Summary of Significant Accounting Policies

Real Estate

Upon acquisitions of real estate, the Company assesses whether the transaction should be accounted for as an asset acquisition or as a business combination by applying a screen to determine whether the integrated set of assets and activities acquired meets the definition of a business. Acquisitions of integrated sets of assets and activities that do not meet the definition of a business are accounted for as asset acquisitions. The Company’s acquisitions of real estate or in-substance real estate generally will not meet the definition of a business because substantially all of the fair value is concentrated in a single identifiable asset or group of similar identifiable assets (i.e. land, buildings, and related intangible assets) or because the acquisition does not include a substantive process in the form of an acquired workforce or an acquired contract that cannot be replaced without significant cost, effort or delay.

The Company assesses the fair value of acquired tangible and intangible assets (including land, buildings, tenant improvements, “above-” and “below-market” leases, leasing and assumed financing origination costs, acquired in-place leases, other identified intangible assets and assumed liabilities (including ground leases)) and allocates the purchase price to the acquired assets and assumed liabilities, including land and buildings as if vacant. The Company assesses fair value based on estimated cash flow projections that utilize discount and/or capitalization rates that it deems appropriate, as well as available market information. Estimates of future cash flows are based on a number of factors including the historical operating results, known and anticipated trends, and market and economic conditions.

The fair value of the tangible assets of an acquired property considers the value of the property as if it were vacant. The Company also considers an allocation of purchase price of other acquired intangibles, including acquired in-place leases that may have a customer relationship intangible value, including (but not limited to) the nature and extent of the existing relationship with the tenants, the tenants’ credit quality and expectations of lease renewals. Based on its acquisitions to date, the Company’s allocation to customer relationship intangible assets has been immaterial.

The Company records acquired “above-” and “below-market” leases at their fair values (using a discount rate which reflects the risks associated with the leases acquired) equal to the difference between (1) the contractual amounts to be paid pursuant to each in-place lease and (2) management’s estimate of fair market lease rates for each corresponding in-place lease, measured over a period equal to the remaining term of the lease for above-market leases and the initial term plus the term of any below-market fixed rate renewal options for below-market leases. Acquired “above-” and “below-market” lease values have been reflected within Prepaid Expenses and Other Assets and Other Liabilities, respectively, in the Company’s Consolidated Balance Sheets. Other intangible assets acquired include amounts for in-place lease values that are based on the Company’s evaluation of the specific characteristics of each tenant’s lease. Factors to be considered include estimates of carrying costs during hypothetical expected lease-up periods considering current market conditions, and costs to execute similar leases. In estimating carrying costs, the Company includes real estate taxes, insurance and other operating expenses and estimates of lost rentals at market rates during the expected lease-up periods, depending on local market conditions. In estimating costs to execute similar leases, the Company considers leasing commissions, legal and other related expenses.

Management reviews its long-lived assets for indicators of impairment following the end of each quarter and when events or changes in circumstances indicate that the carrying amount of the asset may not be recoverable. This evaluation of long-lived assets is dependent on a number of factors, including when there is an event or adverse change in the operating performance of the long-lived asset or a current expectation that, more likely than not, a long-lived asset will be sold or otherwise disposed of significantly before the end of its previously estimated useful life or hold period. An impairment loss is recognized if the carrying amount of an asset is not recoverable and exceeds its fair value. The evaluation of anticipated cash flows is subjective and is based in part on assumptions regarding anticipated hold periods, future occupancy, future rental rates, future capital requirements, discount rates and capitalization rates that could differ materially from actual results in future periods. Because cash flows on properties considered to be “long-lived assets to be held and used” are considered on an undiscounted basis to determine whether an asset may be impaired, the Company’s established strategy of holding properties over the long term directly decreases the likelihood of recording an impairment loss. If the Company’s hold strategy changes or market conditions otherwise dictate a shorter hold, an impairment loss may be recognized, and such loss could be material. If the Company determines that an impairment has occurred, the affected assets must be reduced to their fair value.

Guidance in Accounting Standards Codification (“ASC”) 360 “Property Plant and Equipment” requires that qualifying assets and liabilities and the results of operations that have been sold, or otherwise qualify as “held for sale,” be presented as discontinued operations in all periods presented if the property operations are expected to be eliminated and the Company will not have significant continuing involvement following the sale. Discontinued operations presentation applies only to disposals representing a strategic shift that has (or will have) a major effect on an entity’s operations and financial results (e.g., a disposal of a major geographical area, a major line of business, a major equity method investment or other major parts of an entity). The components of the property’s net income that are reflected as discontinued operations include the net gain (or loss) upon the disposition of the property held for sale, operating results, depreciation and interest expense (if the property is subject to a secured loan). The Company generally considers assets to be “held for sale” when the transaction has been approved by BXP’s Board of Directors, or a committee thereof, and there are no known significant contingencies relating to the sale, such that a sale of the property within one year is considered probable. Following the classification of a property as “held for sale,” no further depreciation is recorded on the assets, and the asset is written down to the lower of carrying value or fair market value, less cost to sell.

Real estate is stated at depreciated cost. A variety of costs are incurred in the acquisition, development and leasing of properties. The cost of buildings and improvements includes the purchase price of property, legal fees and other acquisition costs. The Company capitalizes acquisition costs that it incurs to effect an asset acquisition and expenses acquisition costs that it incurs to effect a business combination, including legal, due diligence and other closing related costs. Costs directly related to the development of properties are capitalized. Capitalized development costs include interest, internal wages, property taxes, insurance, and other project costs incurred during the period of development. After the determination is made to capitalize a cost, it is allocated to the specific

component of the project that benefited from the investment. Determination of when a development project commences and capitalization begins, and when a development project is substantially complete and held available for occupancy and capitalization must cease, involves a degree of judgment. The Company’s capitalization policy on development properties follows the guidance in ASC 835-20 “Capitalization of Interest” and ASC 970 “Real Estate-General.” The costs of land and buildings under development include specifically identifiable costs.

Capitalized costs include pre-construction costs necessary to the development of the property, development costs (including architectural, engineering and design costs), construction costs, interest costs, real estate taxes, salaries and related costs and other costs incurred during the period of development. The Company begins the capitalization of costs during the pre-construction period, which it defines as activities that are necessary for the development of the property. The Company considers a construction project as substantially complete and held available for occupancy upon the completion of tenant improvements, but no later than one year from cessation of major construction activity. The Company ceases capitalization on the portion (1) substantially completed, (2) occupied or held available for occupancy, and capitalizes only those costs associated with the portion under construction or (3) if activities necessary for the development of the property have been suspended. Interest costs capitalized for the years ended December 31, 2023, 2022 and 2021 were approximately $42.6 million, $52.1 million and $53.1 million, respectively. Salaries and related costs capitalized for the years ended December 31, 2023, 2022 and 2021 were approximately $16.1 million, $16.1 million and $13.7 million, respectively.

Expenditures for repairs and maintenance are charged to operations as incurred. Significant betterments are capitalized. When assets are sold or retired, their costs and related accumulated depreciation are removed from the accounts with the resulting gains or losses reflected in net income or loss for the period.

The Company computes depreciation and amortization on properties using the straight-line method based on estimated useful asset lives. The Company allocates the acquisition cost of real estate to its components and depreciates or amortizes these assets (or liabilities) over their useful lives. The amortization of acquired “above-” and “below-market” leases and acquired in-place leases is recorded as an adjustment to revenue and depreciation and amortization, respectively, in the Consolidated Statements of Operations.

Depreciation is computed on a straight-line basis over the estimated useful lives of the assets as follows:


Land improvements						25 to 40 years
Buildings and improvements						10 to 40 years
Tenant improvements						Shorter of useful life or terms of related lease
Furniture, fixtures, and equipment						3 to 10 years

Cash and Cash Equivalents

Cash and cash equivalents consist of cash on hand and investments with maturities of three months or less from the date of purchase. The majority of the Company’s cash and cash equivalents are held at major commercial banks which may at times exceed the Federal Deposit Insurance Corporation limit of $250,000.

Cash Held in Escrows

Escrows include amounts established pursuant to various agreements for security deposits, property taxes, insurance and other costs. Escrows also include cash held by qualified intermediaries for possible investments in like-kind exchanges in accordance with Section 1031 of the Internal Revenue Code, as amended (the “Code”), in connection with sales of the Company’s properties.

Investments in Securities

The Company accounts for investments in equity securities at fair value, with gains or losses resulting from changes in fair value recognized currently in earnings. The Company maintains deferred compensation plans that are designed to allow officers and non-employee directors of BXP to defer a portion of the officer’s current income or the non-employee director’s current compensation on a pre-tax basis and receive a tax-deferred return on these deferrals based on the performance of specific investments selected by the officer or non-employee director. The Company’s obligation under the plans is that of an unsecured promise to pay the deferred compensation to the plan participants in the future. At December 31, 2023 and 2022, the Company had maintained approximately $36.1 million and $32.3 million, respectively, in separate accounts, which are not restricted as to their use. The Company recognized gains (losses) of approximately $5.6 million, $(6.5) million and $5.6 million on its investments in the

accounts associated with the Company’s deferred compensation plans during the years ended December 31, 2023, 2022 and 2021, respectively.

The Company follows ASC 320, ”Investment–Debt and Equity Securities” (“ASC 320”) which requires that debt and equity securities be classified into one of three categories: held to maturity, trading securities or available for sale. At December 31, 2023, the Company had outstanding three-month United States Treasury Bills with a maturity date of January 30, 2024 that were classified as held to maturity because the Company determined that it had the positive intent and ability to hold to maturity. Because these securities were considered a short-term investment, they are reflected at amortized cost within Cash and Cash Equivalents on the Consolidated Balance Sheets. At December 31, 2023, the amortized cost of these securities was approximately $302.7 million. There were no such securities outstanding at December 31, 2022.

Non-Real Estate Investments

The Company measures its investments in non-real estate investments, which are primarily environmentally focused investment funds, at the readily determinable fair value of the investment. Changes in the fair value of these non-real estate investments are included in unrealized gain (loss) on non-real estate investments on the Consolidated Statements of Operations. The Company’s investment in non-real estate investments is shown within Prepaid and Other Assets in the Consolidated Balance Sheet and was approximately $4.6 million and $2.4 million at December 31, 2023 and 2022, respectively. The Company recognized a net unrealized gain (loss) of approximately $0.2 million and $(0.2) million for the years ended December 31, 2023 and 2022, respectively, due to the observable changes in fair value. Prior to the year ended December 31, 2022, the Company had not invested in non-real estate investments

Tenant and Other Receivables

Tenant and other accounts receivable, other than accrued rents receivable, are expected to be collected within one year.

Notes Receivable

The Company accounts for notes receivable at their unamortized cost, net of any unamortized deferred fees or costs, premiums or discounts and an allowance for credit losses. Loan fees and direct costs associated with loans originated by the Company are deferred and amortized using the effective interest method over the term of the note as interest income.

Deferred Charges

Deferred charges include leasing costs and certain financing fees. Leasing costs include acquired intangible in-place lease values and direct and incremental fees and costs incurred in the successful negotiation of leases, including brokerage and other costs which have been deferred and are being amortized on a straight-line basis over the terms of the respective leases. Unamortized leasing costs are charged to expense upon the early termination of the lease. Fully amortized deferred leasing costs are removed from the books upon the expiration of the lease. Financing fees included in deferred charges consist of external fees and costs incurred to obtain the Company’s revolving facility and if applicable, unsecured term loan and construction financing arrangements where there are not sufficient amounts outstanding to report the fees net of the debt liability. Such financing costs have been deferred and are being amortized over the terms of the respective financing and included within interest expense. Unamortized financing costs are charged to expense upon the early repayment or significant modification of the financing. Fully amortized deferred financing costs are removed from the books upon the maturity of the debt.

External fees and costs incurred to obtain mortgage financings and unsecured senior notes have been deferred and are presented as direct deductions from the carrying amounts of the corresponding debt liability. Such financing costs are being amortized over the terms of the respective financing and included within interest expense. Unamortized financing costs are charged to expense upon the early repayment or significant modification of the financing.

Investments in Unconsolidated Joint Ventures

The Company consolidates VIEs in which it is considered to be the primary beneficiary. VIEs are entities in which the equity investors do not have sufficient equity at risk to finance their endeavors without additional financial support or that the holders of the equity investment at risk do not have substantive participating rights. The primary

beneficiary is defined by the entity having both of the following characteristics: (1) the power to direct the activities that, when taken together, most significantly impact the variable interest entity’s performance, and (2) the obligation to absorb losses and the right to receive the returns from the variable interest entity that could potentially be significant to the VIE. For ventures that are not VIEs, the Company consolidates entities for which it has significant decision making control over the ventures’ operations. The Company’s judgment with respect to its level of influence or control of an entity involves the consideration of various factors including the form of the Company’s ownership interest, its representation in the entity’s governance, the size of its investment (including loans), estimates of future cash flows, its ability to participate in policy making decisions and the rights of the other investors to participate in the decision making process and to replace the Company as manager and/or liquidate the venture, if applicable. The Company’s assessment of its influence or control over an entity affects the presentation of these investments in the Company’s consolidated financial statements. In addition to evaluating control rights, the Company consolidates entities in which the outside partner has no substantive kick-out rights to remove the Company as the managing member.

Accounts of the consolidated entity are included in the accounts of the Company and the noncontrolling interest is reflected on the Consolidated Balance Sheets as a component of equity or in temporary equity between liabilities and equity. Investments in unconsolidated joint ventures are recorded initially at cost, and subsequently adjusted for equity in earnings and cash contributions and distributions. Any difference between the carrying amount of these investments on the balance sheet and the underlying equity in net assets is amortized as an adjustment to equity in earnings of unconsolidated joint ventures over the life of the related asset. Under the equity method of accounting, the net equity investment of the Company is reflected within the Consolidated Balance Sheets, and the Company’s share of net income or loss from the joint ventures is included within the Consolidated Statements of Operations. The joint venture agreements may designate different percentage allocations among investors for profits and losses; however, the Company’s recognition of joint venture income or loss generally follows the joint venture’s distribution priorities, which may change upon the achievement of certain investment return thresholds. The Company may account for cash distributions in excess of its investment in an unconsolidated joint venture as income when the Company is not the general partner in a limited partnership and when the Company has neither the requirement nor the intent to provide financial support to the joint venture. The Company classifies distributions received from equity method investees within its Consolidated Statements of Cash Flows using the nature of the distribution approach, which classifies the distributions received on the basis of the nature of the activity or activities of the investee that generated the distribution as either a return on investment (classified as cash inflows from operating activities) or a return of investment (classified as cash inflows from investing activities). The Company’s investments in unconsolidated joint ventures are reviewed for indicators of impairment on a quarterly basis and the Company records impairment charges when events or circumstances change indicating that a decline in the fair values below the carrying amounts has occurred and such decline is other-than-temporary. This evaluation of the investments in unconsolidated joint ventures is dependent on a number of factors, including the performance of each investment and market conditions. The Company will record an impairment charge if it determines that a decline in the fair value below the carrying amount of an investment in an unconsolidated joint venture is other-than-temporary. The fair value is calculated using discounted cash flows which is subjective and considers assumptions regarding future occupancy, future rental rates, future capital requirements, debt interest rates and availability, discount rates and capitalization rates that could differ materially from actual results in future periods. During the year ended December 31, 2023, the Company recognized an other-than-temporary impairment loss on its investments in four joint ventures totaling approximately $272.6 million, as described below in Note 6. During the year ended December 31, 2022, the Company recognized an other-than-temporary impairment loss on its investment in the unconsolidated joint venture that owns Dock 72 in Brooklyn, New York totaling approximately $50.7 million.

To the extent that the Company contributed assets to a joint venture, the Company’s investment in the joint venture was recorded at the Company’s cost basis in the assets that were contributed to the joint venture. To the extent that the Company’s cost basis is different than the basis reflected at the joint venture level, the basis difference is amortized over the life of the related asset and included in the Company’s share of equity in net income of the joint venture. In accordance with the provisions of ASC 610-20 “Gains and Losses from the Derecognition of Nonfinancial Assets” (“ASC 610-20”), the Company will recognize a full gain on both the retained and sold portions of real estate contributed or sold to a joint venture by recognizing its new equity method investment interest at fair value.

The combined summarized financial information of the unconsolidated joint ventures is disclosed in Note 6.

Revenue Recognition

In general, the Company commences lease/rental revenue recognition when the tenant takes possession of the leased space and the leased space is substantially ready for its intended use. Contractual lease/rental revenue is reported on a straight-line basis over the terms of the respective leases. Therefore, the Company recognizes non-cash revenue each reporting period (i.e., the sum of all contractual lease/rental payments due over the term of the lease divided by the number of years in the term). The impact of the straight-line rent adjustment increased revenue by approximately $99.1 million, $108.0 million and $104.3 million for the years ended December 31, 2023, 2022 and 2021, respectively, as the lease/rental revenue recorded exceeded amounts billed. Accrued rental income, as reported on the Consolidated Balance Sheets, represents cumulative lease/rental income earned in excess of rent payments received pursuant to the terms of the individual lease agreements.

The Company must estimate the collectability of its accrued rent and accounts receivable balances related to lease revenue. When evaluating the collectability of tenants’ accrued rent and accounts receivable balances, management considers tenants’ creditworthiness, public statements made by the tenant, current economic trends and changes in tenants’ payment patterns, on a lease-by-lease basis. The Company writes-off the tenant’s receivable balance, including the accrued rent receivable, if the Company considers the balances no longer probable of collection. In addition, tenants in bankruptcy are analyzed and considerations are made in connection with the expected recovery of pre-petition and post-petition claims. If the Company deems the balances no longer probable of collection, the Company writes them off and ceases recognizing lease income, including straight-line rent, unless cash is received. Following a write-off, if (1) the Company subsequently determines that it is probable it will collect substantially all the remaining lessee’s lease payments under the lease term and (2) the lease has not been modified since the write-off, the Company will then reinstate the accrued rent and accounts receivable write-offs, adjusting for the amount related to the period when the lease payments were considered not probable of collection. If the Company’s estimates of collectability differs from the cash received, then the timing and amount of the Company’s reported revenue could be impacted. The credit risk is mitigated by the high quality of the Company’s existing tenant base, reviews of prospective tenants’ risk profiles prior to lease execution and consistent monitoring of the Company’s portfolio to identify potential problem tenants.

The Company recognizes acquired in-place “above-” and “below-market” leases at their fair values as rental revenue over the original term of the respective leases. The impact of the acquired in-place “above-” and “below-market” leases increased revenue by approximately $19.2 million, $9.1 million and $4.2 million for the years ended December 31, 2023, 2022 and 2021, respectively. The following table summarizes the scheduled amortization of the Company’s acquired “above-” and “below-market” lease intangibles for each of the five succeeding years (in thousands).


	Acquired Above-Market Lease Intangibles		Acquired Below-Market Lease Intangibles
2024	$	3,985	$	9,961
2025	1,880		9,756
2026	982		8,602
2027	743		5,432
2028	605		2,125

Recoveries from tenants, consisting of amounts due from tenants for common area maintenance, real estate taxes and other recoverable costs, are recognized as revenue in the period during which the expenses are incurred (See “Leases” below). The Company receives reimbursements of payroll and payroll-related costs from unconsolidated joint venture entities and third-party property owners in connection with management services contracts which the Company reflects on a gross basis instead of on a net basis as the Company has determined that it is the principal and not the agent under these arrangements in accordance with the guidance in ASC 606 “Revenue from Contracts with Customers” (“ASC 606”).

The Company’s parking revenue is derived primarily from monthly and transient daily parking. In addition, the Company has certain lease arrangements for parking accounted for under the guidance in ASC 842 “Leases” (“ASC 842”). The monthly and transient daily parking revenue falls within the scope of ASC 606 and is accounted for at the point in time when control of the goods or services transfers to the customer and the Company’s performance obligation is satisfied.

The Company’s View Boston observatory at The Prudential Center revenue (which is included within Parking and Other Revenue on the Consolidated Statement of Operations) is derived from ticket, special event, food and beverage and merchandise sales. The revenue is recognized when the ticket is used by the purchaser or the special event occurs and when the food and beverage and merchandise are sold.

The Company’s hotel revenue is derived from room rentals and other sources such as charges to guests for telephone service, movie and vending commissions, meeting and banquet room revenue and laundry services. Hotel revenue is recognized as the hotel rooms are occupied and the services are rendered to the hotel customers.

The Company earns management and development fees. Development and management services revenue is earned from unconsolidated joint venture entities and third-party property owners. The Company determined that the performance obligations associated with its development services contracts are satisfied over time and that the Company would recognize its development services revenue under the output method evenly over time from the development commencement date through the substantial completion date of the development management services project due to the stand-ready nature of the contracts. Significant judgments impacting the amount and timing of revenue recognized from the Company’s development services contracts include estimates of total development project costs from which the fees are typically derived and estimates of the period of time until substantial completion of the development project, the period of time over which the development services are required to be performed. The Company recognizes development fees earned from unconsolidated joint venture projects equal to its cost plus profit to the extent of the third party partners’ ownership interest. Property management fees are recorded and earned based on a percentage of collected rents at the properties under management, and not on a straight-line basis, because such fees are contingent upon the collection of rents.

Gains on sales of real estate are recognized pursuant to the provisions included in ASC 610-20. Under ASC 610-20, the Company must first determine whether the transaction is a sale to a customer or non-customer. The Company typically sells real estate on a selective basis and not within the ordinary course of its business and therefore expects that its sale transactions will not be contracts with customers. The Company next determines whether it has a controlling financial interest in the property after the sale, consistent with the consolidation model in ASC 810 “Consolidation” (“ASC 810”). If the Company determines that it does not have a controlling financial interest in the real estate, it evaluates whether a contract exists under ASC 606 and whether the buyer has obtained control of the asset that was sold. The Company recognizes a full gain on sale of real estate when the derecognition criteria under ASC 610-20 have been met.

Leases

Lessee

For leases in which the Company is the lessee (generally ground leases), in accordance with ASC 842 the Company recognizes a right-of-use asset and a lease liability. The Company made the policy election to not apply the requirements of ASC 842 to short-term leases. This policy election is made by class of underlying assets and as described below, the Company considers real estate to be a class of underlying assets, and will not be further delineating it into specific uses of the real estate asset as the risk profiles are similar in nature. For operating leases, the Company will recognize the lease payments it pays in net income on a straight-line basis over the lease term. For finance leases, the Company will recognize interest expense.

The lease liability is equal to the present value of the minimum lease payments in accordance with ASC 842. The Company will use its incremental borrowing rate (“IBR”) to determine the net present value of the minimum lease payments. In order to determine the IBR, the Company utilized a market-based approach to estimate the incremental borrowing rate for each individual lease. The approach required significant judgment. Therefore, the Company utilized different data sets to estimate base IBRs via an analysis of the following weighted-components:

•the interpolated rates from yields on outstanding U.S. Treasury issuances for up to 30 years and for years 31 and beyond, longer-term publicly traded educational institution debt issued by high credit quality educational institutions with maturity dates exceeding 31 years,

•observable mortgage rates spread over U.S. Treasury issuances, and

•unlevered property yields and discount rates.

The Company then applied adjustments to account for considerations related to term and interpolated the IBR.

Lessor

Operating Leases

The Company leases primarily premier workplaces, including office, life sciences, retail and residential space to tenants. These leases may contain extension and termination options that are predominately at the sole discretion of the tenant, provided certain conditions are satisfied. In a few instances, the leases also provide the tenants with options to purchase the underlying asset, which would be exercisable at fair market value. Also, certain of the Company’s retail leases include rental payments that are based on a percentage of the tenant sales in excess of contractual amounts.

Per ASC 842, lessors do not need to separate nonlease components from the associated lease component if certain criteria are met for each class of underlying assets. The guidance in ASC 842 defines “underlying asset” as “an asset that is the subject of a lease for which a right to use that asset has been conveyed to a lessee. The underlying asset could be a physically distinct portion of a single asset.” The Company considers real estate assets as a class of underlying assets and will not be further delineating it into specific uses of the real estate asset as the risk profiles are similar in nature.

Lease components are elements of an arrangement that provide the customer with the right to use an identified asset. Nonlease components are distinct elements of a contract that are not related to securing the use of the leased asset and revenue is recognized in accordance with ASC 606. The Company considers common area maintenance (CAM) and service income associated with tenant work orders to be nonlease components because they represent delivery of a separate service but are not considered a cost of securing the identified asset. In the case of the Company’s business, the identified asset would be the leased real estate (office, life sciences, retail or residential).

The Company assessed and concluded that the timing and pattern of transfer for nonlease components and the associated lease component are the same. The Company determined that the predominant component was the lease component and as such its leases will continue to qualify as operating leases and the Company has made a policy election to account for and present the lease component and the nonlease component as a single component in the revenue section of the Consolidated Statements of Operations labeled Lease.

Recoveries from tenants, consisting of amounts due from tenants for common area maintenance, real estate taxes and other recoverable costs, are recognized as revenue in the period during which the expenses are incurred. The Company recognizes these reimbursements on a gross basis, as the Company obtains control of the goods and services before they are transferred to the tenant.

In addition, in accordance with ASC 842, lessors will only capitalize incremental direct leasing costs.

Sales-Type Leases

Sales-type lease receivables are recognized when a lease qualifies as a sales-type lease. The sales-type lease receivable is initially measured at the present value of the fixed and determinable lease payments, including any guaranteed or unguaranteed residual value of the asset at the end of the lease, discounted at the rate implicit in the lease. The Company evaluates its sales-type lease receivable for impairment under the current expected credit loss standard. Interest income is recognized under the effective interest method. The effective interest method produces a constant yield on the sales-type lease receivable over the term of the lease. Income from these leases are classified as Lease Revenue within the Consolidated Statement of Operations.

Earnings Per Share

Basic earnings per share (“EPS”) is computed by dividing net income available to common shareholders, as adjusted for undistributed earnings (if any) of certain securities issued by BPLP, by the weighted average number of shares of Common Stock outstanding during the year. Diluted EPS reflects the potential dilution that could occur from shares issuable in connection with awards under stock-based compensation plans, including upon the exercise of stock options, and securities of BPLP that are exchangeable for Common Stock.

Earnings Per Common Unit

Basic earnings per common unit is computed by dividing net income available to common unitholders, as adjusted for undistributed earnings (if any) of certain securities issued by BPLP, by the weighted average number of common units outstanding during the year. Diluted earnings per common unit reflects the potential dilution that

could occur from units issuable in connection with awards under BXP’s stock-based compensation plans, including upon the exercise of stock options, and conversion of preferred units of BPLP.

Fair Value of Financial Instruments

The Company follows the authoritative guidance for fair value measurements when valuing its financial instruments for disclosure purposes. The table below presents for December 31, 2023 and December 31, 2022, the financial instruments that are being valued for disclosure purposes, as well as the Level at which they are categorized as defined in ASC 820 “Fair Value Measurements and Disclosures” (“ASC 820”).


Financial Instrument			Level
3-Month United States treasury bills			Level 1
Investment in securities (1)			Level 1
Non-real estate investments (1) (2)			Level 2
Unsecured senior notes (3)			Level 1
Related party note receivable			Level 3
Notes receivable			Level 3
Sales-type lease receivable			Level 3
Mortgage notes payable			Level 3
Unsecured line of credit			Level 3
Unsecured term loan			Level 3

_______________

(1)See “Investments in Securities” and “Non-Real Estate Investments” policies above for information on their fair values.

(2)Included within Prepaid and Other Assets on the Consolidated Balance Sheets.

(3)If trading volume for the period is low, the valuation could be categorized as Level 2.

Because the Company’s valuations of its financial instruments are based on the above Levels and involve the use of estimates, the actual fair values of its financial instruments may differ materially from those estimates.

In addition, the Company’s estimated fair values for these instruments as of the end of the applicable reporting period are not projections of, nor necessarily indicative of, estimated or actual fair values in future reporting periods.

Non-Recurring Fair Value

The following table presents the aggregate carrying value of the Company’s non-recurring fair value financial instruments and the Company’s corresponding estimate of fair value as of December 31, 2023 and December 31, 2022 (in thousands):


	December 31, 2023				December 31, 2022
	Carrying Amount		Estimated Fair Value		Carrying Amount		Estimated Fair Value
3-Month United States Treasury Bills (1)	$	302,746	$	302,746	$	—	$	—

Related party note receivable, net	$	88,779	$	90,593	$	78,576	$	79,220
Note receivable, net	1,714		1,677		—		—
Sales-type lease receivable, net	13,704		13,338		12,811		13,045
Total	$	104,197	$	105,608	$	91,387	$	92,265

Mortgage notes payable, net	$	4,166,379	$	3,705,513	$	3,272,368	$	2,744,479
Unsecured senior notes, net	10,491,617		9,697,393		10,237,968		9,135,512
Unsecured line of credit	—		—		—		—
Unsecured term loan, net	1,198,301		1,196,945		730,000		730,000
Total	$	15,856,297	$	14,599,851	$	14,240,336	$	12,609,991

_______________

(1) Per the guidance in ASC 326, the Company concluded that the risk of nonpayment is nonexistent because the U.S. Government has a long history with no credit losses and therefore, no credit loss allowance was recorded.

Recurring Fair Value

In addition to the financial instruments noted above, the Company uses interest rate swap agreements to manage its interest rate risk (See Note 8). The valuation of these instruments is determined using widely accepted valuation techniques, including discounted cash flow analysis on the expected cash flows of each derivative. This analysis reflects the contractual terms of the derivatives, including the period to maturity, and uses observable market-based inputs, including interest rate curves. To comply with the provisions of ASC 820, the Company incorporates credit valuation adjustments to appropriately reflect both its own nonperformance risk and the respective counterparty’s nonperformance risk in the fair value measurements. Although the Company has determined that the majority of the inputs used to value its derivatives fall within Level 2 of the fair value hierarchy, the credit valuation adjustments associated with its derivatives utilize Level 3 inputs, such as estimates of current credit spreads to evaluate the likelihood of default by the Company and its counterparties. The Company assessed the significance of the impact of the credit valuation adjustments on the overall valuation of its derivative positions and determined that the credit valuation adjustments were not significant to the overall valuation of its derivatives. As a result, the Company has determined that its derivative valuations in their entirety are classified in Level 2 of the fair value hierarchy.

The following table presents the aggregate fair value of the Company’s interest rate swaps as of December 31, 2023 and December 31, 2022 (in thousands):


Fair value	December 31, 2023		December 31, 2022
Interest rate swaps	$	1,976	$	—

Derivative Instruments and Hedging Activities

Derivative instruments and hedging activities require management to make judgments on the nature of its derivatives and their effectiveness as hedges. These judgments determine if the changes in fair value of the derivative instruments are reported in the Consolidated Statements of Operations as a component of net income or as a component of comprehensive income and as a component of equity on the Consolidated Balance Sheets. While management believes its judgments are reasonable, a change in a derivative’s effectiveness as a hedge could materially affect expenses, net income and equity. In general, the Company accounts for both the effective and ineffective portions of changes in the fair value of a derivative in other comprehensive income (loss) and subsequently reclassifies the fair value of the derivative to earnings over the term that the hedged transaction affects earnings and in the same line item as the hedged transaction within the statements of operations.

During the year ended December 31, 2023, to satisfy a lender requirement, the Company entered into two agreements with the same third-party to purchase and sell a $600.0 million interest rate cap. The Company did not elect hedge accounting and as such any change in market value will be recognized in the Consolidated Statement of Operations. The Company recognized a loss from interest rate contracts of approximately $79,000 for the year ended December 31, 2023 due to the observable changes in fair value of its derivatives.

Stock-Based Employee Compensation Plans

At December 31, 2023, the Company had a stock-based employee compensation plan. The Company accounts for the plan under the guidance in ASC 718 “Compensation – Stock Compensation” (“ASC 718”), which revised the fair value based method of accounting for share-based payment liabilities, forfeitures and modifications of stock-based awards and clarified previous guidance in several areas, including measuring fair value, classifying an award as equity or as a liability and attributing compensation cost to reporting periods.

Use of Estimates in the Preparation of Financial Statements

The preparation of financial statements in conformity with accounting principles generally accepted in the United States of America (“GAAP”) requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenue and expenses during the reporting period. These estimates include such items as depreciation and allowances for doubtful accounts. Actual results could differ from those estimates.

The Company bases its estimates on historical experience and on various other assumptions that it considers to be reasonable under the circumstances, including the impact of extraordinary events such as a pandemic, the results of which form the basis for making significant judgments about the carrying values of assets and liabilities,

assessments of future collectability, and other areas of the financial statements that are impacted by the use of estimates. Actual results may differ from these estimates under different assumptions or conditions.

BXP

Equity Offering Costs

Underwriting commissions and offering costs have been reflected as a reduction of additional paid-in capital.

Treasury Stock

BXP’s share repurchases are reflected as treasury stock utilizing the cost method of accounting and are presented as a reduction to consolidated stockholders’ equity.

Dividends

Earnings and profits, which determine the taxability of dividends to stockholders, will differ from income reported for financial reporting purposes due to the differences for federal income tax purposes in the treatment of gains/losses on the sale of real property, revenue and expense recognition, compensation expense, and in the estimated useful lives and basis used to compute depreciation.

The tax treatment of common dividends per share for federal income tax purposes is as follows:


	For the year ended December 31,
	2023					2022					2021
	Per Share			%		Per Share			%		Per Share			%
Ordinary income	$	3.04		72.98	%	$	3.42		86.60	%	$	2.90		73.86	%
Capital gain income	1.12			27.02	%	0.53			13.40	%	0.57			14.57	%
Return of capital	—			—	%	—			—	%	0.45			11.57	%
Total	$	4.16	(1)	100.00	%	$	3.95	(2)	100.00	%	$	3.92	(3)	100.00	%

_____________

(1)The fourth quarter 2023 regular quarterly dividend was $0.98 per common share, of which approximately $0.27 per common share was allocable to 2023 and approximately $0.71 per common share was allocable to 2024.

(2)The fourth quarter 2022 regular quarterly dividend was $0.98 per common share, of which approximately $0.03 per common share was allocable to 2022 and approximately $0.95 per common share was allocable to 2023.

(3)The fourth quarter 2021 regular quarterly dividend was $0.98 per common share, all of which was allocable to 2022.

Income Taxes

BXP has elected to be treated as a REIT under Sections 856 through 860 of the Code, commencing with its taxable year ended December 31, 1997. As a result, it generally will not be subject to federal corporate income tax on its taxable income that is distributed to its stockholders. A REIT is subject to a number of organizational and operational requirements, including a requirement that it currently distribute at least 90% of its annual taxable income (with certain adjustments). BXP’s policy is to distribute at least 100% of its taxable income. Accordingly, the only provision for federal income taxes in the accompanying consolidated financial statements relates to BXP’s consolidated taxable REIT subsidiaries. BXP’s taxable REIT subsidiaries did not have significant tax provisions or deferred income tax items. BXP has no uncertain tax positions recognized as of December 31, 2023 and 2022. At December 31, 2023, BXP’s tax returns for the years 2020 forward remain subject to examination by the major tax jurisdictions under the statute of limitations.

The Company owns a hotel property that it leases to one of its taxable REIT subsidiaries and that is managed by Marriott International, Inc. The hotel taxable REIT subsidiary, a wholly owned subsidiary of BPLP, is the lessee pursuant to the lease for the hotel property. As lessor, BPLP is entitled to a percentage of gross receipts from the hotel property. Marriott International, Inc. continues to manage the hotel property under the Marriott name and under terms of a management agreement. The hotel taxable REIT subsidiary is subject to tax at the federal and state level and, accordingly, if applicable, BXP has recorded a tax provision in its Consolidated Statements of Operations for the years ended December 31, 2023, 2022 and 2021.

Certain entities included in BXP’s consolidated financial statements are subject to certain state and local taxes. These taxes are recorded as operating expenses in the accompanying consolidated financial statements.

BPLP

Income Taxes

The partners are required to report their respective share of BPLP’s taxable income or loss on their respective tax returns and are liable for any related taxes thereon. Accordingly, the only provision for federal income taxes in the accompanying consolidated financial statements relates to BPLP’s consolidated taxable REIT subsidiaries. BPLP’s taxable REIT subsidiaries did not have significant tax provisions or deferred income tax items. BPLP has no uncertain tax positions recognized as of December 31, 2023 and 2022. At December 31, 2023, BPLP’s tax returns for 2020 and subsequent years remain subject to examination by the major tax jurisdictions under the statute of limitations.

The Company owns a hotel property which is managed through a taxable REIT subsidiary. The hotel taxable REIT subsidiary, a wholly owned subsidiary of BPLP, is the lessee pursuant to the lease for the hotel property. As lessor, BPLP is entitled to a percentage of gross receipts from the hotel property. Marriott International, Inc. continues to manage the hotel property under the Marriott name and under terms of a management agreement. The hotel taxable REIT subsidiary is subject to tax at the federal and state level and, accordingly, if applicable, BPLP has recorded a tax provision in its Consolidated Statements of Operations for the years ended December 31, 2023, 2022 and 2021.

Certain entities included in BPLP’s consolidated financial statements are subject to certain state and local taxes. These taxes are recorded as operating expenses in the accompanying consolidated financial statements.

Newly Issued Accounting Pronouncements

In August 2023, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) 2023-05, “Business Combinations - Joint Venture Formations (Subtopic 805-60)” (“ASU 2023-05”). ASU 2023-05 is intended to (1) address accounting for contributions made to a joint venture upon formation and (2) reduce diversity in practice. ASU 2023-05 is effective for all joint ventures formed on or after January 1, 2025, with early adoption permitted. The Company is currently assessing the potential impact that the adoption of ASU 2023-05 will have on the Company's consolidated financial statements.

In November 2023, the FASB issued ASU 2023-07, “Segment Reporting (Topic 280): Improvements to Reportable Segment Disclosures” (“ASU 2023-07”). ASU 2023-07 improves reportable segment disclosure requirements for public business entities primarily through enhanced disclosures about significant segment expenses that are regularly provided to the chief operating decision maker and included within each reported measure of segment profit (referred to as the “significant expense principle”). ASU 2023-07 is effective for fiscal years beginning after December 15, 2023 and interim periods within fiscal years beginning after December 15, 2024, with early adoption permitted. The Company is currently assessing the potential impact that the adoption of ASU 2023-07 will have on the Company's consolidated financial statements.

In December 2023, the FASB issued ASU 2023-09, “Income Taxes (Topic 740): Improvements to Income Tax Disclosures” (“ASU 2023-09”). ASU 2023-09 enhances income tax disclosure should be enhanced to

provide information to better assess how an entity’s operations and related tax risks and tax planning and operational opportunities affect its tax rate and prospects for future cash flows. ASU 2023-09 is effective for fiscal years beginning after December 15, 2024. Early adoption is permitted for annual financial statements that have not yet been issued or made available for issuance. The Company is currently assessing the potential impact that the adoption of ASU 2023-09 will have on the Company's consolidated financial statements.

Summary Of Significant Accounting Policies Fair Value of Derivatives (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Interest Rate Swap
Derivatives, Fair Value [Line Items]
Interest rate swaps	$ 1,976	$ 0

SEC Schedule, Article 12-28, Real Estate and Accumulated Depreciation Roll Forward (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate [Roll Forward]
Balance at the beginning of the year	$ 25,744,214	$ 24,108,220	$ 23,303,303
Additions to / improvements of real estate	1,811,036	2,228,000	1,145,084
Assets sold/written-off	(133,779)	(592,006)	(340,167)
Balance at the end of the year	27,421,471	25,744,214	24,108,220
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Accumulated Depreciation [Roll Forward]
Balance at the beginning of the year	6,260,992	5,848,183	5,501,637
Depreciation expense	714,191	646,020	623,854
Assets sold/written-off	(133,779)	(233,211)	(277,308)
Balance at the end of the year	6,841,404	6,260,992	5,848,183
Boston Properties Limited Partnership
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate [Roll Forward]
Balance at the beginning of the year	25,376,700	23,734,833	22,926,494
Additions to / improvements of real estate	1,811,036	2,228,000	1,145,084
Assets sold/written-off	(132,530)	(586,133)	(336,745)
Balance at the end of the year	27,055,206	25,376,700	23,734,833
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Accumulated Depreciation [Roll Forward]
Balance at the beginning of the year	6,143,384	5,736,240	5,396,111
Depreciation expense	707,183	638,538	615,553
Assets sold/written-off	(132,530)	(231,394)	(275,424)
Balance at the end of the year	$ 6,718,037	$ 6,143,384	$ 5,736,240

Segment Information (Schedule Of Segment Reporting By Geographic Area And Property Type) (Details) - USD ($)
$ in Thousands

12 Months Ended

Dec. 31, 2023

Dec. 31, 2022

Dec. 31, 2021

^[1]

$ 3,119,999

$ 2,968,412

$ 2,792,160

^[1]

47,592

57,181

42,668

^[1]

$ 3,214,948

$ 3,065,075

$ 2,848,437

100.00%

$ 1,160,697

$ 1,078,487

$ 996,707

23,250

29,583

24,444

$ 1,216,172

$ 1,135,548

$ 1,034,149

100.00%

$ 1,998,776

$ 1,929,527

$ 1,814,288

Company's Share of Net Operating Income: % of Grand Totals

100.00%

100.00%

Boston [Member]

^[1]

$ 1,093,840

$ 1,005,156

$ 930,560

^[1]

16,452

15,086

13,397

^[1]

$ 1,157,649

$ 1,059,724

$ 957,566

36.01%

34.58%

33.62%

$ 393,339

$ 360,218

$ 322,298

6,378

5,961

5,811

$ 431,942

$ 393,657

$ 341,107

35.51%

34.66%

32.98%

$ 725,707

$ 666,067

$ 616,459

Company's Share of Net Operating Income: % of Grand Totals

36.31%

34.52%

33.98%

36.35%

34.75%

33.98%

Los Angeles [Member]

^[1]

$ 3,890

$ 0

^[1]

^[1]

$ 3,890

$ 0

0.12%

0.00%

$ 1,431

$ 0

$ 1,431

$ 0

0.12%

0.00%

$ 2,459

$ 0

Company's Share of Net Operating Income: % of Grand Totals

0.12%

0.00%

2.61%

2.81%

2.98%

New York [Member]

^[1]

$ 1,053,615

$ 1,031,479

$ 1,012,172

^[1]

^[1]

$ 1,053,615

$ 1,031,479

$ 1,012,172

32.77%

33.65%

35.53%

$ 415,831

$ 391,293

$ 379,267

$ 415,831

$ 391,293

$ 379,267

34.19%

34.46%

36.67%

$ 637,784

$ 640,186

$ 632,905

Company's Share of Net Operating Income: % of Grand Totals

31.91%

33.18%

34.88%

25.62%

26.32%

28.18%

San Francisco [Member]

^[1]

$ 539,904

$ 534,397

$ 508,620

^[1]

14,102

14,769

3,892

^[1]

$ 554,006

$ 549,166

$ 512,512

17.23%

17.92%

17.99%

$ 194,205

$ 183,353

$ 168,040

9,255

11,371

6,717

$ 203,460

$ 194,724

$ 174,757

16.73%

17.15%

16.90%

$ 350,546

$ 354,442

$ 337,755

Company's Share of Net Operating Income: % of Grand Totals

17.54%

18.37%

18.62%

18.66%

19.49%

20.27%

Seattle

^[1]

$ 63,830

$ 31,978

$ 0

^[1]

^[1]

$ 63,830

$ 31,978

$ 0

1.99%

1.04%

0.00%

$ 12,387

$ 8,386

$ 0

$ 12,387

$ 8,386

$ 0

1.02%

0.74%

0.00%

$ 51,443

$ 23,592

$ 0

Company's Share of Net Operating Income: % of Grand Totals

2.57%

1.22%

0.00%

3.00%

1.66%

0.14%

Washington, DC [Member]

^[1]

$ 364,920

$ 365,402

$ 340,808

^[1]

17,038

27,326

25,379

^[1]

$ 381,958

$ 392,728

$ 366,187

11.88%

12.81%

12.86%

$ 143,504

$ 135,237

$ 127,102

7,617

12,251

11,916

$ 151,121

$ 147,488

$ 139,018

12.43%

12.99%

13.45%

$ 230,837

$ 245,240

$ 227,169

Company's Share of Net Operating Income: % of Grand Totals

11.55%

12.71%

12.52%

13.76%

14.97%

14.45%

Hotel [Member]

^[1]

$ 47,357

$ 39,482

$ 13,609

Hotel [Member] | Boston [Member]

32,225

27,478

12,998

^[1]

47,357

39,482

13,609

Hotel [Member] | Los Angeles [Member]

32,225

27,478

12,998

^[1]

Hotel [Member] | New York [Member]

^[1]

Hotel [Member] | San Francisco [Member]

^[1]

Hotel [Member] | Seattle

^[1]

Hotel [Member] | Washington, DC [Member]

^[1]

Noncontrolling interest - property partnerships [Member]

Noncontrolling interest - property partnerships [Member] | Boston [Member]

(194,365)

(191,812)

(186,304)

Noncontrolling interest - property partnerships [Member] | Los Angeles [Member]

(45,730)

(45,822)

(43,232)

Noncontrolling interest - property partnerships [Member] | New York [Member]

Noncontrolling interest - property partnerships [Member] | San Francisco [Member]

(148,635)

(145,990)

(143,072)

Noncontrolling interest - property partnerships [Member] | Seattle

Noncontrolling interest - property partnerships [Member] | Washington, DC [Member]

Unconsolidated Joint Ventures [Member] | Boston [Member]

107,756

Unconsolidated Joint Ventures [Member] | Los Angeles [Member]

34,376

34,233

16,551

Unconsolidated Joint Ventures [Member] | New York [Member]

48,818

53,023

51,641

Unconsolidated Joint Ventures [Member] | San Francisco [Member]

14,314

1,594

(664)

Unconsolidated Joint Ventures [Member] | Seattle

16,203

12,785

14,152

Unconsolidated Joint Ventures [Member] | Washington, DC [Member]

7,494

7,690

2,498

39,490

36,756

23,578

Company's Share [Member]

Company's Share [Member] | Boston [Member]

1,965,106

1,883,796

1,735,740

Company's Share [Member] | Los Angeles [Member]

714,353

654,478

589,778

Company's Share [Member] | New York [Member]

51,277

53,023

51,641

Company's Share [Member] | San Francisco [Member]

503,463

495,790

489,169

Company's Share [Member] | Seattle

366,749

367,227

351,907

Company's Share [Member] | Washington, DC [Member]

58,937

31,282

2,498

$ 270,327

$ 281,996

$ 250,747

[1]	Rental Revenue is equal to Total Revenue per the Company’s Consolidated Statements of Operations, less Development and Management Services Revenue and Direct Reimbursements of Payroll and Related Costs from Management Services Contracts Revenue per the Consolidated Statements of Operations.

Real Estate Schedule of Real Estate Properties (Details) - USD ($)
$ in Thousands

Dec. 31, 2023

Dec. 31, 2022

Land

$ 5,251,224

$ 5,189,811

401,680

^[1]

237,510

Land held for future development

^[1]

324,298

167,351

^[3]

697,061

^[2]

721,501

Buildings and improvements

16,607,756

15,820,724

Tenant improvements

3,592,172

3,200,743

53,716

50,310

Construction in progress

547,280

406,574

Less: accumulated depreciation

27,475,187

25,794,524

(6,881,728)

(6,298,082)

20,593,459

19,496,442

Land

5,156,515

5,095,102

401,680

^[1]

237,510

Land held for future development

^[1]

324,298

167,351

^[3]

697,061

^[4]

721,501

Buildings and improvements

16,336,200

15,547,919

Tenant improvements

3,592,172

3,200,743

53,716

50,310

Construction in progress

547,280

406,574

Less: accumulated depreciation

27,108,922

25,427,010

(6,758,361)

(6,180,474)

Schedule of Equity Method Investments [Line Items]

$ 20,350,561

$ 19,246,536

[1]	See Note 4.
[2]	Includes pre-development costs.
[3]	Includes pre-development costs.
[4]	Includes pre-development costs.

Noncontrolling Interests Common Units Distributions (Details) - $ / shares	Oct. 31, 2023	Jul. 31, 2023	Apr. 28, 2023	Jan. 30, 2023	Oct. 31, 2022	Jul. 29, 2022	Apr. 29, 2022	Jan. 28, 2022	Oct. 29, 2021	Jul. 30, 2021	Apr. 30, 2021	Jan. 28, 2021	Dec. 18, 2023
Dividends Payable [Line Items]
Distributions Payable, Amount Per Unit													$ 0.98
Dividends, Per Unit, Cash Paid	$ 0.98	$ 0.98	$ 0.98	$ 0.98	$ 0.98	$ 0.98	$ 0.98	$ 0.98	$ 0.98	$ 0.98	$ 0.98	$ 0.98
Boston Properties Limited Partnership
Dividends Payable [Line Items]
Distributions Payable, Amount Per Unit													0.98
Dividends, Per Unit, Cash Paid	0.98	0.98	0.98	0.98	0.98	0.98	0.98	0.98	0.98	0.98	0.98	0.98
Boston Properties Limited Partnership \| Op units and LTIP units
Dividends Payable [Line Items]
Distributions Payable, Amount Per Unit													0.98
Dividends, Per Unit, Cash Paid	0.98	0.98	0.98	0.98	0.98	0.98	0.98	0.98	0.98	0.98	0.98	0.98
Boston Properties Limited Partnership \| Unvested MYLTIP Units [Member]
Dividends Payable [Line Items]
Distributions Payable, Amount Per Unit													$ 0.098
Dividends, Per Unit, Cash Paid	$ 0.098	$ 0.098	$ 0.098	$ 0.098	$ 0.098	$ 0.098	$ 0.098	$ 0.098	$ 0.098	$ 0.098	$ 0.098	$ 0.098

Stock Option and Incentive Plan Stock and Units (Narrative) (Details) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2023 USD ($) days $ / shares shares	Dec. 31, 2022 USD ($) $ / shares shares	Dec. 31, 2021 USD ($) $ / shares shares	Feb. 07, 2023 USD ($)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares issued \| shares	157,019,766	156,836,767
Stock based compensation expense \| $	$ 50,200	$ 50,700	$ 49,700
Common Stock, Value, Issued \| $	$ 1,569	$ 1,568
Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares issued \| shares	73,762	41,818	57,383
LTIP Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Value Of LTIP Units Issued \| $	$ 29,900	$ 28,900	$ 23,800
Weighted average price (per unit) \| $ / shares	$ 69.29	$ 103.06	$ 84.43
Expected life assumed to calculate per unit fair value per LTIP unit (in years)	5 years 8 months 12 days	5 years 8 months 12 days	5 years 8 months 12 days
Risk-free rate	3.67%	1.71%	0.65%
Expected price volatility	32.00%	31.00%	30.00%
Employee Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares issued \| shares	18,552	9,813	9,846
Weighted Average Price of Shares Purchased \| $ / shares	$ 51.93	$ 87.30	$ 89.73
Number of Business Days, Average Closing Price \| days	10
MYLTIP 2023
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Value of MYLTIP Awards \| $				$ 13,100
Boston Properties Limited Partnership \| LTIP Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares issued \| shares	430,824	280,616	281,640
Boston Properties Limited Partnership \| MYLTIP 2023
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares issued \| shares	322,053
Boston Properties Limited Partnership \| MYLTIP 2022
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares issued \| shares		254,061
Boston Properties Limited Partnership \| MYLTIP 2021
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares issued \| shares			352,021
Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Employee and director payment per share (in dollars per share) \| $ / shares	$ 0.01
Common Stock, Value, Issued \| $	$ 5,400	$ 4,700	$ 5,800
Common Stock Weighted Average Price (in dollars per share) \| $ / shares	$ 72.57	$ 111.47	$ 100.60
LTIP and MYLTIP Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Employee and director payment per share (in dollars per share) \| $ / shares	$ 0.25
Ltips (including vested MYLTIPS) And Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation expenses \| $	$ 20,700
Unvested MYLTIP Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation expenses \| $	$ 300
Weighted-average period (years)	2 years 6 months

Investment in Unconsolidated Joint Ventures (Narrative) (Details)

1 Months Ended

12 Months Ended

Dec. 31, 2023

USD ($)

ft²

Dec. 14, 2023

USD ($)

ft²

floor

Oct. 31, 2023

USD ($)

Oct. 02, 2023

USD ($)

Sep. 13, 2023

USD ($)

ft²

Sep. 06, 2023

USD ($)

ft²

Sep. 05, 2023

USD ($)

Aug. 11, 2023

Jul. 28, 2023

USD ($)

Integer

Jul. 27, 2023

USD ($)

Jun. 28, 2023

Jun. 27, 2023

USD ($)

Jun. 02, 2023

Apr. 21, 2023

ft²

Year

Apr. 20, 2023

USD ($)

Jan. 31, 2023

USD ($)

ft²

Building

Vehicles

Aug. 13, 2023

Dec. 31, 2023

USD ($)

ft²

Dec. 31, 2022

USD ($)

Dec. 31, 2021

USD ($)

Dec. 13, 2023

Oct. 30, 2023

ft²

Sep. 12, 2023

USD ($)

Sep. 08, 2023

USD ($)

Sep. 01, 2023

ft²

Jun. 30, 2023

ft²

Jun. 05, 2023

USD ($)

ft²

Jun. 04, 2023

USD ($)

Interest and Other Income

$ 69,964,000

$ 11,940,000

$ 5,704,000

$ 13,953,000

13,953,000

13,028,000

Schedule of Equity Method Investments [Line Items]

10,058,000

Mortgages [Member]

Related party note receivable

4,200,000,000

$ 88,779,000

78,576,000

3 Hudson Boulevard [Member]

Schedule of Equity Method Investments [Line Items]

25.00%

Interest Expense, Long-Term Debt

2,000,000

$ 28,000,000

3 Hudson Boulevard [Member] | Related Party

Schedule of Equity Method Investments [Line Items]

Interest and Other Income

$ 8,900,000

$ 5,600,000

3,600,000

Schedule of Equity Method Investments [Line Items]

^[1]

26.69%

Office Tower Developer LLC

$ 33,400,000

Schedule of Equity Method Investments [Line Items]

Gateway Commons Complex [Member]

50.00%

Schedule of Equity Method Investments [Line Items]

Podium Developer LLC [Member]

50.00%

Schedule of Equity Method Investments [Line Items]

BP/CRF Metropolitan Square LLC [Member]

50.00%

Schedule of Equity Method Investments [Line Items]

^[2]

20.00%

Schedule of Equity Method Investments [Line Items]

$ 35,800,000

Platform 16

^[1],[3]

55.00%

$ 155,200,000

6.00%

Discount Rate

12.00%

Schedule of Equity Method Investments [Line Items]

^[1],[4]

71.11%

360 PAS Holdco LLC | Scenario, Plan | Joint Venture Partner [Member]

$ 54,000,000

Schedule of Equity Method Investments [Line Items]

29.00%

Schedule of Equity Method Investments [Line Items]

^[1],[5]

33.67%

$ 29,900,000

Schedule of Equity Method Investments [Line Items]

Santa Monica Business Park [Member] | Joint Venture Partner [Member]

^[6]

55.00%

Schedule of Equity Method Investments [Line Items]

Hotel Tower Developer LLC [Member]

45.00%

Schedule of Equity Method Investments [Line Items]

50.00%

Schedule of Equity Method Investments [Line Items]

Gain on Sale of Investments

$ (272,603,000)

^[7]

$ (50,705,000)

^[7]

10,257,000

^[8]

35,756,000

^[9]

28,412,000

^[9],[10]

$ 13,900,000

13,900,000

Unconsolidated Joint Ventures [Member] | 200 Fifth Avenue JV LLC

2,737,000

$ 0

Schedule of Equity Method Investments [Line Items]

Unconsolidated Joint Ventures [Member] | Platform 16

33,400,000

Schedule of Equity Method Investments [Line Items]

Unconsolidated Joint Ventures [Member] | 360 PAS Holdco LLC

155,200,000

Schedule of Equity Method Investments [Line Items]

Unconsolidated Joint Ventures [Member] | Safeco Plaza REIT LLC

54,000,000

Schedule of Equity Method Investments [Line Items]

Unconsolidated Properties | Unconsolidated Joint Ventures [Member]

29,900,000

Schedule of Equity Method Investments [Line Items]

Worldgate Drive | Unconsolidated Properties

272,600,000

Schedule of Equity Method Investments [Line Items]

Payments to Acquire Interest in Joint Venture

50.00%

$ 17,000,000

Number of buildings | Building

350,000

Number of parking space | Vehicles

1,200

Area of Land | a

7750 Wisconsin Avenue [Member] | Unconsolidated Properties

Schedule of Equity Method Investments [Line Items]

50.00%

Debt Instrument, Description of Variable Rate Basis

736,000

Construction Loan

$ 252,600,000

Term Secured Overnight Finance Rate (“SOFR”)

LIBOR

London Interbank Offered Rate (“LIBOR”)

Extension Option (in years)

1.25%

7750 Wisconsin Avenue [Member] | Unconsolidated Properties | Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate

Schedule of Equity Method Investments [Line Items]

500 North Capitol Street, NW | Unconsolidated Properties

1.35%

Schedule of Equity Method Investments [Line Items]

30.00%

231,000

Debt, Weighted Average Interest Rate

$ 105,000,000

6.83%

500 North Capitol Street, NW | Unconsolidated Properties | Related Party

Schedule of Equity Method Investments [Line Items]

Debt, Weighted Average Interest Rate

$ 105,000,000

6.83%

500 North Capitol Street, NW | Unconsolidated Properties | Company's Share [Member] | Related Party

Schedule of Equity Method Investments [Line Items]

Related party note receivable

$ 10,500,000

3 Hudson Boulevard [Member] | Unconsolidated Properties

Schedule of Equity Method Investments [Line Items]

Debt Instrument, Description of Variable Rate Basis

25.00%

LIBOR

3.50%

$ 80,000,000

Extension Option (in days)

30 days

Extension Option Two (in days)

180 days

3 Hudson Boulevard [Member] | Unconsolidated Properties | Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate

Schedule of Equity Method Investments [Line Items]

3 Hudson Boulevard [Member] | Unconsolidated Properties | Extended Maturity

3.61%

Schedule of Equity Method Investments [Line Items]

Debt Instrument, Term

30 days

100 Causeway Street [Member] | Construction Loans

Schedule of Equity Method Investments [Line Items]

Extension Option (in years) | Integer

Repayments of Construction Loans Payable

$ 336,600,000

$ 340,600,000

$ 4,000,000

100 Causeway Street [Member] | Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate | Construction Loans

Schedule of Equity Method Investments [Line Items]

100 Causeway Street [Member] | Office Tower Developer LLC

1.48%

1.60%

Schedule of Equity Method Investments [Line Items]

100 Causeway Street [Member] | Extended Maturity | Construction Loans

50.00%

Schedule of Equity Method Investments [Line Items]

Fiscal Period Duration

1 year

100 Causeway Street [Member] | Unconsolidated Properties

Schedule of Equity Method Investments [Line Items]

634,000

751 Gateway | Unconsolidated Properties

95.00%

Schedule of Equity Method Investments [Line Items]

49.00%

231,000

Hub on Causeway - Podium | Unconsolidated Properties | Podium Developer LLC [Member]

100.00%

Schedule of Equity Method Investments [Line Items]

50.00%

383,000

94.00%

Extension Option (in years)

2.50%

2.35%

Repayments of Construction Loans Payable

$ 154,300,000

$ 174,300,000

$ 20,000,000

Derivative, Fixed Interest Rate

$ 154,300,000

7.35%

Metropolitan Square

Schedule of Equity Method Investments [Line Items]

Metropolitan Square | Senior Loans

$ 420,000,000

Schedule of Equity Method Investments [Line Items]

Metropolitan Square | Junior Loans

305,000,000

Schedule of Equity Method Investments [Line Items]

Metropolitan Square | Scenario, Plan

$ 115,000,000

Schedule of Equity Method Investments [Line Items]

Debt Instrument, Unused Borrowing Capacity, Amount

$ 100,000,000

Metropolitan Square | Scenario, Plan | Affiliated Entity

Schedule of Equity Method Investments [Line Items]

Loans and Leases Receivable, Loans in Process

$ 20,000,000

Metropolitan Square | Unconsolidated Properties | BP/CRF Metropolitan Square LLC [Member]

Schedule of Equity Method Investments [Line Items]

20.00%

657,000

$ 35,800,000

Platform 16 | Unconsolidated Properties

$ (1,500,000)

Schedule of Equity Method Investments [Line Items]

Platform 16 | Unconsolidated Properties | Platform 16

390,000

Schedule of Equity Method Investments [Line Items]

360 Park Avenue South | 360 PAS Holdco LLC

55.00%

Schedule of Equity Method Investments [Line Items]

$ 54,000,000

360 Park Avenue South | 360 PAS Holdco LLC (indirect ownership)

5.50%

Schedule of Equity Method Investments [Line Items]

71.00%

Net Working Capital, Including Cash Acquired from Acquisition

450,000

$ 25,400,000

Number of floors | floor

360 Park Avenue South | 360 PAS Holdco LLC (indirect ownership) | Joint Venture Partner [Member]

Schedule of Equity Method Investments [Line Items]

29.00%

360 Park Avenue South | 360 PAS Holdco LLC (indirect ownership) | Mortgages [Member] | Joint Venture Partner [Member]

$ 1

Schedule of Equity Method Investments [Line Items]

360 Park Avenue South | Unconsolidated Properties | 360 PAS Holdco LLC

$ 220,000,000

Schedule of Equity Method Investments [Line Items]

200 Fifth Avenue | 200 Fifth Avenue JV LLC

450,000

Schedule of Equity Method Investments [Line Items]

$ 33,400,000

200 Fifth Avenue | Unconsolidated Properties

5.00%

Discount Rate

8.00%

Schedule of Equity Method Investments [Line Items]

Safeco Plaza | Safeco Plaza REIT LLC

855,000

Schedule of Equity Method Investments [Line Items]

$ 29,900,000

Safeco Plaza | Unconsolidated Properties

5.50%

Discount Rate

8.00%

Schedule of Equity Method Investments [Line Items]

780,000

Schedule of Equity Method Investments [Line Items]

1,200,000

Net Working Capital, Including Cash Acquired from Acquisition

$ 38,000,000

20,000,000

Santa Monica Business Park [Member] | Mortgages [Member]

29,900,000

Schedule of Equity Method Investments [Line Items]

Santa Monica Business Park [Member] | Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate | Mortgages [Member]

$ 300,000,000

Schedule of Equity Method Investments [Line Items]

Debt Instrument, Description of Variable Rate Basis

SOFR

1.38%

$ 300,000,000

Santa Monica Business Park [Member] | Santa Monica Business Park [Member]

295,500,000

Schedule of Equity Method Investments [Line Items]

Santa Monica Business Park [Member] | Unconsolidated Properties | Santa Monica Business Park [Member]

29,900,000

Schedule of Equity Method Investments [Line Items]

55.00%

Net Working Capital, Including Cash Acquired from Acquisition

38,000,000

$ 20,000,000

Hub on Causeway - Hotel Air Rights | Unconsolidated Properties | Hotel Tower Developer LLC [Member]

Schedule of Equity Method Investments [Line Items]

50.00%

Lease Income

$ 4,500,000

18,600,000

Share-Based Payment Arrangement [Abstract]

$ 2,700,000

[1]	During the year ended December 31, 2023, the Company recognized an other-than-temporary impairment loss on its investment.
[2]	During the year ended December 31, 2023, the Company completed a restructuring of its ownership in Metropolitan Square, as described below in this Note 6.
[3]	At December 31, 2022, this entity was a VIE.
[4]	On December 14, 2023, the Company completed the acquisition of all of one of its joint venture partners ownership interest. As a result of this acquisition, at December 31, 2023, the Company’s ownership includes (1) a 35.79% direct interest in the joint venture, (2) an additional 35.02% indirect ownership in the joint venture, and (3) an additional 1% interest in the entity through which the partner owns its interest in the joint venture. The Company’s partner will fund required capital until its aggregate investment is approximately 29% of all capital contributions; thereafter, the partners will fund required capital according to their percentage interests. At December 31, 2022, the Company’s ownership included (1) a 35.79% direct interest in the joint venture, (2) an additional 5.837% indirect ownership in the joint venture, and (3) an additional 1% interest in each of the two entities through which each partner owns its interest in the joint venture.
[5]	The Company’s ownership includes (1) a 33.0% direct interest in the joint venture, and (2) an additional 1% interest in each of the two entities through which each partner owns its interest in the joint venture.
[6]	During the year ended December 31, 2023, the Company completed the acquisition of its joint venture partner’s 45% ownership interest in Santa Monica Business Park, as described below in this Note 6 and Note 3.
[7]	During the year ended December 31, 2023, the Company recognized an other-than-temporary impairment loss on its investments in Platform 16, 360 Park Avenue South, 200 Fifth Avenue and Safeco Plaza of approximately $155.2 million, $54.0 million, $33.4 million and $29.9 million, respectively, as described below in this Note 6. During the year ended December 31, 2022, the Company recognized an other-than-temporary impairment loss on its investment in the unconsolidated joint venture that owns Dock 72 in Brooklyn, New York totaling approximately $50.7 million.
[8]	During the year ended December 31, 2021, the Company completed the sale of its 50% ownership interest in Annapolis Junction NFM LLC. The Company recognized a gain on sale of investment of approximately $10.3 million.
[9]	During the year ended December 31, 2023, the Company completed a restructuring of its ownership in Metropolitan Square, as described below in this Note 6.
[10]	During the year ended December 31, 2023, the Company acquired its joint venture partner’s 45% ownership interest in Santa Monica Business Park, as described below in this Note 6.

Stock Option and Incentive Plan

12 Months Ended

Dec. 31, 2023

Stock Option and Incentive Plan

15. Stock Option and Incentive Plan

At the Company’s 2021 annual meeting of stockholders held on May 20, 2021, its stockholders approved the Boston Properties, Inc. 2021 Stock Incentive Plan (the “2021 Plan”). The 2021 Plan replaced the Boston Properties, Inc. 2012 Stock Option and Incentive Plan (the “2012 Plan”) and no further awards will be issued under the 2012 Plan. The material features of the 2021 Plan include, among other things: (i) the maximum number of shares of common stock reserved and available for issuance under the 2021 Plan is 5,400,000 shares less one share for every one share that was granted between March 4, 2021 and May 19, 2021 under the 2012 Plan, (ii) shares of common stock underlying awards granted under the 2021 Plan or the 2012 Plan that are forfeited, canceled or otherwise terminated (other than by exercise) will be added back to the shares of common stock available for issuance under the 2021 Plan and, with respect to “full-value” awards under the 2021 Plan or the 2012 Plan, shares tendered or held back for taxes and shares previously reserved for issuance pursuant to such an award to the extent that such shares are not issued and are no longer issuable pursuant to such an award (e.g., in the event that a full-value award that may be settled in cash or by issuance of shares of common stock is settled in cash) will be added back to the shares available for issuance under the 2021 Plan, (iii) the award of stock options (both incentive and non-qualified options), stock appreciation rights, restricted stock units, restricted stock, unrestricted stock, dividend equivalent rights, cash-based awards and other equity-based awards (including LTIP Units) is permitted, (iv) stock options may not be repriced and “underwater” stock options may not be exchanged for another award or cash without stockholder approval; and (v) the term of the 2021 Plan ends ten years from the date

of stockholder approval, or May 20, 2031.

On January 25, 2023, BXP’s Compensation Committee approved the grant of 2023 MYLTIP awards under the 2021 Plan to certain executive officers of BXP, effective February 7, 2023. The 2023 MYLTIP awards consist of two, equally weighted (50% each) components that utilize BXP’s TSR over a three-year measurement period as the performance metrics.

Total earned awards under the 2023 MYLTIP, if any, will equal the sum of the number of LTIP Units earned under the two components and will range from zero to a maximum of 322,053 LTIP Units with a target of approximately 161,026 LTIP Units and linear interpolation between zero and maximum. Earned awards (if any) will vest 100% on February 6, 2026, but, in general, may not be converted, redeemed, sold or otherwise transferred for one additional year thereafter. The 2023 MYLTIP awards are in the form of LTIP Units issued on the grant date, and they are subject to forfeiture to the extent awards are not earned. Prior to the performance measurement date holders of the 2023 MYLTIP Units are only entitled to one-tenth (10%) of the regular quarterly distributions payable on common partnership units. Following the completion of the three-year performance period, the Company will also make a “catch-up” cash payment on the 2023 MYLTIP Units that are ultimately earned in an amount equal to the regular and special distributions, if any, declared during the performance period on a number of shares of BXP’s Common Stock equal to the number of 2023 MYLTIP Units that are earned, less the distributions actually paid to holders of 2023 MYLTIP Units during the performance period on all of the awarded 2023 MYLTIP Units. Under ASC 718 “Compensation - Stock Compensation,” the 2023 MYLTIP awards have an aggregate value of approximately $13.1 million, which amount will generally be amortized into earnings under the graded vesting method.

On February 3, 2023, the measurement period for the Company’s 2020 MYLTIP awards ended and, based on BXP’s relative TSR performance, the final payout was determined to be 50% of target, or an aggregate of approximately $3.8 million (after giving effect to employee separations). As a result, an aggregate of 152,460 2020 MYLTIP Units that had been previously granted were automatically forfeited.

On February 4, 2022, the measurement period for the Company’s 2019 MYLTIP awards ended and, based on BXP’s relative TSR performance, the final payout was determined to be 69.0% of target, or an aggregate of approximately $8.6 million (after giving effect to employee separations). As a result, an aggregate of 144,043 2019 MYLTIP Units that had been previously granted were automatically forfeited.

On February 5, 2021, the measurement period for the Company’s 2018 MYLTIP awards ended and, based on BXP’s relative TSR performance, the final awards were determined to be 29.2% of target, or an aggregate of approximately $4.6 million (after giving effect to employee separations). As a result, an aggregate of 285,925 2018 MYLTIP Units that had been previously granted were automatically forfeited.

BXP issued 73,762, 41,818 and 57,383 shares of restricted common stock and BPLP issued 430,824, 280,616 and 281,640 LTIP Units to employees and non-employee directors under the 2012 Plan and the 2021 Plan during the years ended December 31, 2023, 2022 and 2021, respectively. BXP did not issue any non-qualified stock options under the 2012 Plan or 2021 Plan during the years ended December 31, 2023, 2022 and 2021. BPLP issued 322,053 2023 MYLTIP Units, 254,061 2022 MYLTIP Units and 352,021 2021 MYLTIP Units to employees under the 2012 Plan and 2021 Plan during the years ended December 31, 2023, 2022 and 2021, respectively. Employees and non-employee directors paid $0.01 per share of restricted common stock and $0.25 per LTIP Unit and MYLTIP Unit. When issued, LTIP Units are not economically equivalent in value to a share of Common Stock, but over time can increase in value to one-for-one parity with Common Stock if there is sufficient appreciation in the value of the Company’s assets. The aggregate value of the LTIP Units is included in noncontrolling interests in the Consolidated Balance Sheets of BXP and BPLP. A majority of the grants of restricted common stock and LTIP Units to employees vest in four equal annual installments. Restricted common stock is measured at fair value on the date of grant based on the number of shares granted and the closing price of BXP’s Common Stock on the date of grant as quoted on the New York Stock Exchange. Such value is recognized as an expense ratably over the corresponding employee service period. Because the 2012 OPP Units and 2013 - 2023 MYLTIP Units are subject to both a service condition and a market condition, the Company recognizes the related compensation expense under the graded vesting attribution method. Under the graded vesting attribution method, each portion of the award that vests at a different date is accounted for as a separate award and recognized over the period appropriate to that portion so that the compensation cost for each portion should be recognized in full by the time that portion vests. The Company recognizes forfeitures as they occur on its awards of stock-based compensation. Dividends paid on both vested and unvested shares of restricted stock are charged directly to Dividends in Excess of Earnings in BXP’s Consolidated Balance Sheets and Partners’ Capital in BPLP’s Consolidated Balance Sheets. Aggregate stock-based compensation expense associated with restricted stock, LTIP Units and 2020 - 2023

MYLTIP Units was approximately $50.2 million, $50.7 million and $49.7 million for the years ended December 31, 2023, 2022 and 2021, respectively. At December 31, 2023, there was (1) an aggregate of approximately $20.7 million of unrecognized compensation expense related to unvested restricted stock and LTIP Units and (2) an aggregate of approximately $0.3 million of unrecognized compensation expense related to unvested 2021 - 2023 MYLTIP Units that is expected to be recognized over a weighted-average period of approximately 2.5 years.

The shares of restricted stock were valued at approximately $5.4 million ($72.57 per share weighted-average), $4.7 million ($111.47 per share weighted-average) and $5.8 million ($100.60 per share weighted-average) for the years ended December 31, 2023, 2022 and 2021, respectively.

LTIP Units were valued using a Monte Carlo simulation method model in accordance with the provisions of ASC 718. LTIP Units issued during the years ended December 31, 2023, 2022 and 2021 were valued at approximately $29.9 million, $28.9 million and $23.8 million, respectively. The weighted-average per unit fair value of LTIP Unit grants in 2023, 2022 and 2021 was $69.29, $103.06 and $84.43, respectively. The per unit fair value of each LTIP Unit granted in 2023, 2022 and 2021 was estimated on the date of grant using the following assumptions; an expected life of 5.7 years, 5.7 years and 5.7 years, a risk-free interest rate of 3.67%, 1.71% and 0.65% and an expected price volatility of 32.0%, 31.0% and 30.0%, respectively.

There were no non-qualified stock options granted during the years ended December 31, 2023, 2022 and 2021.

A summary of the status of BXP’s stock options as of December 31, 2023, 2022 and 2021 and changes during the years then ended are presented below:


	Shares	Weighted-Average Exercise Price
Outstanding at December 31, 2020	351,561	$	96.97
Exercised	(247,920)	$	96.95
Outstanding at December 31, 2021	103,641	$	97.01
Exercised	—	$	—
Outstanding at December 31, 2022	103,641	$	97.01
Forfeited	(103,641)	$	—
Outstanding at December 31, 2023	—	$	—

There were no stock options outstanding as of December 31, 2023. In addition, BXP had 103,641 options exercisable and vested at a weighted-average exercise price of $97.01 at December 31, 2022 and 2021.

BXP adopted the 1999 Non-Qualified Employee Stock Purchase Plan (the “Stock Purchase Plan”) to encourage the ownership of Common Stock by eligible employees. The Stock Purchase Plan became effective on January 1, 1999 with an aggregate maximum of 250,000 shares of Common Stock available for issuance. The Stock Purchase Plan provides for eligible employees to purchase on the business day immediately following the end of the biannual purchase periods (i.e., January 1-June 30 and July 1-December 31) shares of Common Stock at a purchase price equal to 85% of the average closing prices of the Common Stock during the last ten business days of the purchase period. BXP issued 18,552, 9,813 and 9,846 shares with the weighted-average purchase price equal to $51.93 per share, $87.30 per share and $89.73 per share under the Stock Purchase Plan during the years ended December 31, 2023, 2022 and 2021, respectively.

Future Minimum Rent (Details) $ in Thousands	12 Months Ended
Future Minimum Rent (Details) $ in Thousands	Dec. 31, 2023 USD ($)	Dec. 31, 2022	Dec. 31, 2021
Leases [Abstract]
2024	$ 2,420,047
2025	2,444,826
2026	2,379,371
2027	2,281,437
2028	2,140,919
Thereafter	$ 15,592,965
Schedule of Future Minimum Lease Payments
Number Of Tenants Above Concentration Amount.	0	0	0
Revenue Benchmark [Member] \| Customer Concentration Risk
Concentration Risk [Line Items]
Concentration Risk, Percentage	10.00%	10.00%	10.00%

Investments in Unconsolidated Joint Ventures (Statements of Operations of the Joint Ventures) (Details) - USD ($)
$ in Thousands

12 Months Ended

Oct. 31, 2023

Dec. 31, 2023

Dec. 31, 2022

Dec. 31, 2021

Dec. 14, 2023

Schedule of Equity Method Investments [Line Items]

$ 3,273,569

$ 3,108,581

$ 2,888,621

Expenses

4,313

2,905

5,036

830,813

749,775

717,336

2,239,227

2,050,056

1,920,581

(45,182)

(579,572)

(437,139)

(423,346)

Income (Loss) from Equity Method Investments

10,058

Net Loss

291,424

1,020,584

631,932

(239,543)

(59,840)

(2,570)

99,100

108,000

104,300

19,200

9,100

4,200

Schedule of Equity Method Investments [Line Items]

^[1]

612,589

512,078

383,649

Expenses

Operating

239,947

198,632

158,498

301

837

470

197,228

181,041

147,121

437,476

380,510

306,089

(3)

(1,327)

Unrealized gain (loss) on derivative instruments

(227,537)

(154,065)

(108,884)

6,582

(1,681)

Company's share of net income (loss)

2,737

Net Loss

(56,272)

(22,143)

(31,324)

(19,599)

(2,551)

(10,254)

Gain on Sale of Investments

10,257

^[2]

35,756

^[3]

28,412

^[3],[4]

Income (Loss) from Equity Method Investments

(272,603)

^[5]

(50,705)

^[5]

Basis differential

^[6]

(11,509)

(6,584)

(2,573)

(239,543)

(59,840)

(2,570)

28,700

62,900

17,200

Unconsolidated Joint Ventures [Member] | Unconsolidated Properties

800

400

$ 400

Annapolis Junction NFM, LLC [Member]

272,600

Annapolis Junction NFM, LLC [Member] | Unconsolidated Joint Ventures [Member]

50.00%

Gain on Sale of Investments

$ 10,300

Colorado Center [Member] | Unconsolidated Joint Ventures [Member]

Dock 72 [Member] | Unconsolidated Joint Ventures [Member]

1,500

$ 500

$ 800

50,700

$ 33,400

200 Fifth Avenue JV LLC | Unconsolidated Joint Ventures [Member]

^[7]

26.69%

$ 33,400

$ 29,900

Safeco Plaza REIT LLC | Unconsolidated Joint Ventures [Member]

^[7],[8]

33.67%

$ 29,900

Platform 16

$ 155,200

Platform 16 | Unconsolidated Joint Ventures [Member]

^[7],[9]

55.00%

$ 155,200

$ 54,000

360 PAS Holdco LLC | Unconsolidated Joint Ventures [Member]

^[7],[10]

71.11%

$ 54,000

Santa Monica Business Park [Member] | Joint Venture Partner [Member]

^[11]

55.00%

Hotel Tower Developer LLC [Member]

45.00%

Hotel Tower Developer LLC [Member] | Unconsolidated Properties | Hub on Causeway - Hotel Air Rights

50.00%

$ 2,700

50.00%

[1]	Includes straight-line rent adjustments of approximately $28.7 million, $62.9 million and $17.2 million for the years ended December 31, 2023, 2022 and 2021, respectively.
[2]	During the year ended December 31, 2021, the Company completed the sale of its 50% ownership interest in Annapolis Junction NFM LLC. The Company recognized a gain on sale of investment of approximately $10.3 million.
[3]	During the year ended December 31, 2023, the Company completed a restructuring of its ownership in Metropolitan Square, as described below in this Note 6.
[4]	During the year ended December 31, 2023, the Company acquired its joint venture partner’s 45% ownership interest in Santa Monica Business Park, as described below in this Note 6.
[5]	During the year ended December 31, 2023, the Company recognized an other-than-temporary impairment loss on its investments in Platform 16, 360 Park Avenue South, 200 Fifth Avenue and Safeco Plaza of approximately $155.2 million, $54.0 million, $33.4 million and $29.9 million, respectively, as described below in this Note 6. During the year ended December 31, 2022, the Company recognized an other-than-temporary impairment loss on its investment in the unconsolidated joint venture that owns Dock 72 in Brooklyn, New York totaling approximately $50.7 million.
[6]	Includes straight-line rent adjustments of approximately $1.5 million, $0.5 million and $0.8 million for the years ended December 31, 2023, 2022 and 2020, respectively. Also includes net above-/below-market rent adjustments of approximately $0.8 million, $0.4 million and $0.4 million for the years ended December 31, 2023, 2022 and 2021, respectively.
[7]	During the year ended December 31, 2023, the Company recognized an other-than-temporary impairment loss on its investment.
[8]	The Company’s ownership includes (1) a 33.0% direct interest in the joint venture, and (2) an additional 1% interest in each of the two entities through which each partner owns its interest in the joint venture.
[9]	At December 31, 2022, this entity was a VIE.
[10]	On December 14, 2023, the Company completed the acquisition of all of one of its joint venture partners ownership interest. As a result of this acquisition, at December 31, 2023, the Company’s ownership includes (1) a 35.79% direct interest in the joint venture, (2) an additional 35.02% indirect ownership in the joint venture, and (3) an additional 1% interest in the entity through which the partner owns its interest in the joint venture. The Company’s partner will fund required capital until its aggregate investment is approximately 29% of all capital contributions; thereafter, the partners will fund required capital according to their percentage interests. At December 31, 2022, the Company’s ownership included (1) a 35.79% direct interest in the joint venture, (2) an additional 5.837% indirect ownership in the joint venture, and (3) an additional 1% interest in each of the two entities through which each partner owns its interest in the joint venture.
[11]	During the year ended December 31, 2023, the Company completed the acquisition of its joint venture partner’s 45% ownership interest in Santa Monica Business Park, as described below in this Note 6 and Note 3.

Stock Option and Incentive Plan (Narrative) (Details) - USD ($) $ / shares in Units, $ in Thousands						12 Months Ended
	Feb. 07, 2023	Feb. 03, 2023	Feb. 04, 2022	May 20, 2021	Feb. 05, 2021	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting Period						4 years
Stock Issued During Period, Shares, Share-based Compensation, Forfeited						(103,641)
Weighted Average Exercise Price						$ 0	$ 97.01	$ 97.01	$ 96.97
2021 Stock Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-Based Compensation Arrangement by Share-Based Payment Award, Plan Expiration Period				10 years
MYLTIP 2023
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Terms of Award	The 2023 MYLTIP awards consist of two, equally weighted (50% each) components that utilize BXP’s TSR over a three-year measurement period as the performance metrics.
Distributions percent before measurement date	10.00%
Vesting Period	3 years
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights	Earned awards (if any) will vest 100% on February 6, 2026, but, in general, may not be converted, redeemed, sold or otherwise transferred for one additional year thereafter.
Value of MYLTIP Awards	$ 13,100
MYLTIP 2020 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Value of MYLTIP Awards		$ 3,800
Final awards percentage of target		50.00%
Forfeitures, in units		152,460
MYLTIP 2019 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Value of MYLTIP Awards			$ 8,600
Final awards percentage of target			69.00%
Forfeitures, in units			144,043
stock option
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Granted						0	0	0
MYLTIP 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Value of MYLTIP Awards					$ 4,600
Final awards percentage of target					29.20%
Forfeitures, in units					285,925
Employee Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock available for issuance						250,000
Employee discount						85.00%
Weighted Average Price of Shares Purchased						$ 51.93	$ 87.30	$ 89.73
Minimum [Member] \| MYLTIP 2023 \| Boston Properties Limited Partnership
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock available for issuance	0
Maximum [Member] \| 2021 Stock Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock available for issuance				5,400,000
Maximum [Member] \| MYLTIP 2023 \| Boston Properties Limited Partnership
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock available for issuance	322,053
Target \| MYLTIP 2023 \| Boston Properties Limited Partnership
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock available for issuance	161,026

Real Estate (Narrative) (Details)
$ in Thousands

1 Months Ended

12 Months Ended

Dec. 14, 2023

USD ($)

ft²

buildings

Dec. 31, 2023

USD ($)

ft²

Real_Estate_Properties

Dec. 31, 2023

USD ($)

ft²

Real_Estate_Properties

Dec. 31, 2022

USD ($)

Dec. 31, 2021

USD ($)

Dec. 13, 2023

USD ($)

Nov. 30, 2023

ft²

Nov. 13, 2023

Oct. 05, 2023

ft²

Sep. 26, 2023

ft²

Jul. 20, 2023

ft²

Jun. 01, 2023

ft²

Apr. 29, 2023

ft²

Jan. 30, 2023

ft²

Jan. 05, 2023

ft²

Net Income (Loss) Attributable to Parent

$ 3,273,569

$ 3,108,581

$ 2,888,621

190,215

848,947

505,195

Carying value of the Company's investment in unconsolidated joint ventures

830,813

749,775

$ 717,336

$ 1,377,319

$ 1,715,911

Carying value of the Company's investment in unconsolidated joint ventures

^[1]

55.00%

^[2]

$ 164,735

Joint Venture Partner [Member] | Santa Monica Business Park [Member]

45.00%

Construction in Progress

Number of real estate properties | Real_Estate_Properties

2,700,000

Land Subject to Ground Leases | a

Number of real estate properties | buildings

1,200,000

Lessee, Finance Lease, Remaining Lease Term

75 years

Net Working Capital, Including Cash Acquired from Acquisition

$ 38,000

20,000

$ 29,900

Net Income (Loss) Attributable to Parent

$ 3,900

$ (900)

Land subject to ground lease, percentage

70.00%

Santa Monica Business Park [Member] | Santa Monica Business Park [Member]

Santa Monica Business Park [Member] | Mortgages [Member]

$ 29,900

Santa Monica Business Park [Member] | Company's Share [Member]

$ 300,000

Carying value of the Company's investment in unconsolidated joint ventures

$ 149,900

290 Binney | Construction in Progress

566,000

100.00%

300 Binney Street

195,000

300 Binney Street | Noncontrolling Interest [Member]

$ 11,000

Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners

45.00%

300 Binney Street | Construction in Progress

236,000

100.00%

2100 Pennsylvania Avenue

476,000

View Boston

140 Kendrick Street - Building A

63,000

104,000

180 CityPoint [Member]

329,000

103 CityPoint

113,000

105 Carnegie Center

105 Carnegie Center | Future construction

70,000

Schedule Of Reconciliation Of Net Operating Income To Net Income

73,000

[1]	During the year ended December 31, 2023, the Company completed the acquisition of its joint venture partner’s 45% ownership interest in Santa Monica Business Park, as described below in this Note 6 and Note 3.
[2]	Investments with deficit balances aggregating approximately $39.9 million and $85.4 million at December 31, 2023 and December 31, 2022, respectively, are included within Other Liabilities in the Company’s Consolidated Balance Sheets.

Audit Information	12 Months Ended
Audit Information	Dec. 31, 2023
Auditor [Line Items]
Auditor Name	PricewaterhouseCoopers LLP
Auditor Location	Boston, Massachusetts
Auditor Firm ID	238
Boston Properties Limited Partnership
Auditor [Line Items]
Auditor Name	PricewaterhouseCoopers LLP
Auditor Location	Boston, Massachusetts
Auditor Firm ID	238

Sales Type Lease Maturity Schedule (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Sales-Type and Direct Financing Leases, Lease Receivable, Payments to be Received, Fiscal Year Maturity [Abstract]
2024	$ 31	$ 0
2025	124	31
2026	372	124
2027	756	372
2026	775	756
Thereafter	267,474	268,249
Total lease payments to be received	269,532	269,532
Interest portion	255,579	256,504
Sales-type lease receivable, net	13,953	13,028
Sales-type Lease, Unguaranteed Residual Asset	18	17
Current expected credit loss adjustment	(267)	(234)
Sales-type lease receivable, net	$ 13,704	$ 12,811

Segment Information (Tables)

12 Months Ended

Dec. 31, 2023

Segment Reporting [Abstract]

BXP


	Year ended December 31,
		2023		2022		2021
		(in thousands)
Net income attributable to Boston Properties, Inc. common shareholders		$	190,215	$	848,947	$	496,223
Add:
Preferred stock redemption charge		—		—		6,412
Preferred dividends		—		—		2,560
Noncontrolling interest—common units of the Operating Partnership		22,548		96,780		55,931
Noncontrolling interests in property partnerships		78,661		74,857		70,806
Interest expense		579,572		437,139		423,346
Losses from early extinguishment of debt		—		—		45,182
Losses from interest rate contracts		79		—		—
Net operating income from unconsolidated joint ventures		160,695		146,081		107,756
Loss from unconsolidated joint ventures		239,543		59,840		2,570
Depreciation and amortization expense		830,813		749,775		717,336
Transaction costs		4,313		2,905		5,036
Payroll and related costs from management services contracts		17,771		15,450		12,487
General and administrative expense		170,158		146,378		151,573
Less:
Net operating income attributable to noncontrolling interests in property partnerships		194,365		191,812		186,304
Unrealized gain (loss) on non-real estate investment		239		(150)		—
Gains (losses) from investments in securities		5,556		(6,453)		5,626
Other income - assignment fee		—		6,624		—
Interest and other income (loss)		69,964		11,940		5,704
Gain on sales-type lease		—		10,058		—
Gains on sales of real estate		517		437,019		123,660
Direct reimbursements of payroll and related costs from management services contracts		17,771		15,450		12,487
Development and management services revenue		40,850		28,056		27,697
Company’s share of Net Operating Income		$	1,965,106	$	1,883,796	$	1,735,740

BPLP


	Year ended December 31,
		2023		2022		2021
		(in thousands)
Net income attributable to Boston Properties Limited Partnership common unitholders		$	219,771	$	957,265	$	561,993
Add:
Preferred unit redemption charge		—		—		6,412
Preferred distributions		—		—		2,560
Noncontrolling interests in property partnerships		78,661		74,857		70,806
Interest expense		579,572		437,139		423,346
Losses from early extinguishment of debt		—		—		45,182
Losses from interest rate contracts		79		—		—
Net operating income from unconsolidated joint ventures		160,695		146,081		107,756
Loss from unconsolidated joint ventures		239,543		59,840		2,570
Depreciation and amortization expense		823,805		742,293		709,035
Transaction costs		4,313		2,905		5,036
Payroll and related costs from management services contracts		17,771		15,450		12,487
General and administrative expense		170,158		146,378		151,573
Less:
Net operating income attributable to noncontrolling interests in property partnerships		194,365		191,812		186,304
Unrealized gain (loss) on non-real estate investment		239		(150)		—
Gains (losses) from investments in securities		5,556		(6,453)		5,626
Other income - assignment fee		—		6,624		—
Interest and other income (loss)		69,964		11,940		5,704
Gain on sales-type lease		—		10,058		—
Gains on sales of real estate		517		441,075		125,198
Direct reimbursements of payroll and related costs from management services contracts		17,771		15,450		12,487
Development and management services revenue		40,850		28,056		27,697
Company’s share of Net Operating Income		$	1,965,106	$	1,883,796	$	1,735,740

Schedule Of Segment Information By Geographic Area And Property Type

Information by geographic area and property type (dollars in thousands):

For the year ended December 31, 2023:


	Boston			Los Angeles			New York			San Francisco			Seattle			Washington, DC			Total
Rental Revenue: (1)
Premier Workplace	$	1,093,840		$	3,890		$	1,053,615		$	539,904		$	63,830		$	364,920		$	3,119,999
Residential	16,452			—			—			14,102			—			17,038			47,592
Hotel	47,357			—			—			—			—			—			47,357
Total	1,157,649			3,890			1,053,615			554,006			63,830			381,958			3,214,948
% of Grand Totals	36.01		%	0.12		%	32.77		%	17.23		%	1.99		%	11.88		%	100.00		%
Rental Expenses:
Premier Workplace	393,339			1,431			415,831			194,205			12,387			143,504			1,160,697
Residential	6,378			—			—			9,255			—			7,617			23,250
Hotel	32,225			—			—			—			—			—			32,225
Total	431,942			1,431			415,831			203,460			12,387			151,121			1,216,172
% of Grand Totals	35.51		%	0.12		%	34.19		%	16.73		%	1.02		%	12.43		%	100.00		%
Net operating income	$	725,707		$	2,459		$	637,784		$	350,546		$	51,443		$	230,837		$	1,998,776
% of Grand Totals	36.31		%	0.12		%	31.91		%	17.54		%	2.57		%	11.55		%	100.00		%
Less: Net operating income attributable to noncontrolling interests in property partnerships	(45,730)			—			(148,635)			—			—			—			(194,365)
Add: Company’s share of net operating income from unconsolidated joint ventures	34,376			48,818			14,314			16,203			7,494			39,490			160,695
Company’s share of net operating income	$	714,353		$	51,277		$	503,463		$	366,749		$	58,937		$	270,327		$	1,965,106
% of Grand Totals	36.35		%	2.61		%	25.62		%	18.66		%	3.00		%	13.76		%	100.00		%

_______________

(1)Rental Revenue is equal to Total Revenue per the Company’s Consolidated Statements of Operations, less Development and Management Services Revenue and Direct Reimbursements of Payroll and Related Costs from Management Services Contracts Revenue per the Consolidated Statements of Operations.

For the year ended December 31, 2022:


	Boston			Los Angeles			New York			San Francisco			Seattle			Washington, DC			Total
Rental Revenue: (1)
Premier Workplace	$	1,005,156		$	—		$	1,031,479		$	534,397		$	31,978		$	365,402		$	2,968,412
Residential	15,086			—			—			14,769			—			27,326			57,181
Hotel	39,482			—			—			—			—			—			39,482
Total	1,059,724			—			1,031,479			549,166			31,978			392,728			3,065,075
% of Grand Totals	34.58		%	—		%	33.65		%	17.92		%	1.04		%	12.81		%	100.00		%
Rental Expenses:
Premier Workplace	360,218			—			391,293			183,353			8,386			135,237			1,078,487
Residential	5,961			—			—			11,371			—			12,251			29,583
Hotel	27,478			—			—			—			—			—			27,478
Total	393,657			—			391,293			194,724			8,386			147,488			1,135,548
% of Grand Totals	34.66		%	—		%	34.46		%	17.15		%	0.74		%	12.99		%	100.00		%
Net operating income	$	666,067		$	—		$	640,186		$	354,442		$	23,592		$	245,240		$	1,929,527
% of Grand Totals	34.52		%	—		%	33.18		%	18.37		%	1.22		%	12.71		%	100.00		%
Less: Net operating income attributable to noncontrolling interests in property partnerships	(45,822)			—			(145,990)			—			—			—			(191,812)
Add: Company’s share of net operating income from unconsolidated joint ventures	34,233			53,023			1,594			12,785			7,690			36,756			146,081
Company’s share of net operating income	$	654,478		$	53,023		$	495,790		$	367,227		$	31,282		$	281,996		$	1,883,796
% of Grand Totals	34.75		%	2.81		%	26.32		%	19.49		%	1.66		%	14.97		%	100.00		%

_______________

For the year ended December 31, 2021:


	Boston			Los Angeles			New York			San Francisco			Seattle			Washington, DC			Total
Rental Revenue: (1)
Premier Workplace	$	930,560		$	—		$	1,012,172		$	508,620		$	—		$	340,808		$	2,792,160
Residential	13,397			—			—			3,892			—			25,379			42,668
Hotel	13,609			—			—			—			—			—			13,609
Total	957,566			—			1,012,172			512,512			—			366,187			2,848,437
% of Grand Totals	33.62		%	—		%	35.53		%	17.99		%	—		%	12.86		%	100.00		%
Rental Expenses:
Premier Workplace	322,298			—			379,267			168,040			—			127,102			996,707
Residential	5,811			—			—			6,717			—			11,916			24,444
Hotel	12,998			—			—			—			—			—			12,998
Total	341,107			—			379,267			174,757			—			139,018			1,034,149
% of Grand Totals	32.98		%	—		%	36.67		%	16.90		%	—		%	13.45		%	100.00		%
Net operating income	$	616,459		$	—		$	632,905		$	337,755		$	—		$	227,169		$	1,814,288
% of Grand Totals	33.98		%	—		%	34.88		%	18.62		%	—		%	12.52		%	100.00		%
Less: Net operating income attributable to noncontrolling interests in property partnerships	(43,232)			—			(143,072)			—			—			—			(186,304)
Add: Company’s share of net operating income (loss) from unconsolidated joint ventures	16,551			51,641			(664)			14,152			2,498			23,578			107,756
Company’s share of net operating income	$	589,778		$	51,641		$	489,169		$	351,907		$	2,498		$	250,747		$	1,735,740
% of Grand Totals	33.98		%	2.98		%	28.18		%	20.27		%	0.14		%	14.45		%	100.00		%

_______________

Noncontrolling Interests (Narrative) (Details) - Boston Properties Limited Partnership	Dec. 31, 2023 shares
OP Units [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Noncontrolling Interest, Outstanding	16,508,277
LTIP Units [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Noncontrolling Interest, Outstanding	2,065,861
2012 OPP and 2013-2020 MYLTIP [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Noncontrolling Interest, Outstanding	480,511
MYLTIP 2021
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Noncontrolling Interest, Outstanding	349,267
MYLTIP 2022
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Noncontrolling Interest, Outstanding	252,151
MYLTIP 2023
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Noncontrolling Interest, Outstanding	322,053

Lessee, Lease Cost and Other Information (Details)
$ in Thousands

12 Months Ended

Dec. 31, 2023

USD ($)

Dec. 31, 2022

USD ($)

Dec. 31, 2021

USD ($)

Amortization of right-of-use asset

Operating lease costs

^[1]

$ 14,451

$ 12,700

$ 13,151

^[2]

2,821

697

547

Interest on lease liabilities

^[3]

$ 13,747

$ 3,236

$ 2,471

Operating leases, Weighted-average remaining lease term

70 years

49 years

Finance leases, Weighted-average remaining lease term

60 years

68 years

Operating leases, Weighted-average discount rate

6.60%

5.70%

Finance leases, Weighted-average discount rate

6.10%

6.20%

Finance leases under development

Operating leases under development

[1]	One of the operating leases relate to assets under development for a portion of the year ended December 31, 2023 and as such, the operating lease costs were capitalized. For December 31, 2022 and 2021, no operating leases related to assets under development.
[2]	The finance leases relate to either land, buildings or assets that remain in development. For land leases classified as finance leases because of a purchase option that the Company views as an economic incentive, the Company follows its existing policy and does not depreciate land because it is assumed to have an indefinite life. For all other finance leases, the Company would amortize the right of use asset over the shorter of the useful life of the asset or the lease term. If the finance lease relates to a property under development, the amortization of the right of use asset may be eligible for capitalization. For assets under development, depreciation may commence once the asset is placed in-service and depreciation would be recognized in accordance with the Company’s policy.
[3]	One, one and two of the finance leases relate to assets under development for all or a portion of the years ended December 31, 2023, December 31, 2022 and December 31, 2021, respectively, and as such, a portion of the interest amount was capitalized.

Debt (Tables)

12 Months Ended

Dec. 31, 2023

Debt Disclosure [Abstract]

Schedule Of Aggregate Principal Payments On Mortgage Notes

Contractual aggregate principal payments of mortgage notes payable at December 31, 2023 are as follows (dollars in thousands):


	Principal Payments
2024	$	—
2025	300,000
2026	—
2027	2,300,000
2028	600,000
Thereafter	1,000,000
Total aggregate principal payments	4,200,000
Less:
Deferred financing costs, net	29,270
Fair value debt adjustment	4,351
Total carrying value of mortgage notes payable, net	$	4,166,379

Schedule of Long-term Debt Instruments

The following summarizes the unsecured senior notes outstanding as of December 31, 2023 (dollars in thousands):


	Coupon/Stated Rate		Effective Rate(1)		Principal Amount		Maturity Date(2)
10.5 Year Unsecured Senior Notes (3)	3.800	%	3.916	%	$	700,000	February 1, 2024
7 Year Unsecured Senior Notes	3.200	%	3.350	%	850,000		January 15, 2025
10 Year Unsecured Senior Notes	3.650	%	3.766	%	1,000,000		February 1, 2026
10 Year Unsecured Senior Notes	2.750	%	3.495	%	1,000,000		October 1, 2026
5 Year Unsecured Senior Notes	6.750	%	6.924	%	750,000		December 1, 2027
10 Year Unsecured Senior Notes	4.500	%	4.628	%	1,000,000		December 1, 2028
10 Year Unsecured Senior Notes	3.400	%	3.505	%	850,000		June 21, 2029
10.5 Year Unsecured Senior Notes	2.900	%	2.984	%	700,000		March 15, 2030
10.75 Year Unsecured Senior Notes	3.250	%	3.343	%	1,250,000		January 30, 2031
11 Year Unsecured Senior Notes	2.550	%	2.671	%	850,000		April 1, 2032
12 Year Unsecured Senior Notes	2.450	%	2.524	%	850,000		October 1, 2033
10.7 Year Unsecured Senior Notes	6.500	%	6.619	%	750,000		January 15, 2034
Total principal					10,550,000
Less:
Net unamortized discount					13,302
Deferred financing costs, net					45,081
Total					$	10,491,617

_______________

(1)Yield on issuance date including the effects of discounts on the notes, settlements of interest rate contracts and the amortization of financing costs.

(2)No principal amounts are due prior to maturity.

(3)See Note 17.

Tabular disclosure of long-debt instruments or arrangements, including identification, terms, features, collateral requirements and other information necessary to a fair presentation. These are debt arrangements that originally required repayment more than twelve months after issuance or greater than the normal operating cycle of the entity, if longer.

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Summary Of Significant Accounting Policies [Line Items]

Summary Of Significant Accounting Policies of Tax Treatment of Common Dividends Per Share for Federal Tax Purposes (Details) - $ / shares

3 Months Ended

12 Months Ended

Oct. 31, 2023

Jul. 31, 2023

Apr. 28, 2023

Jan. 30, 2023

Oct. 31, 2022

Jul. 29, 2022

Apr. 29, 2022

Jan. 28, 2022

Oct. 29, 2021

Jul. 30, 2021

Apr. 30, 2021

Jan. 28, 2021

Dec. 31, 2022

Dec. 31, 2021

Dec. 31, 2023

Dec. 31, 2022

Dec. 31, 2021

Dec. 18, 2023

Dividends Treatment For Federal Tax Purposes, Percentage

$ 4.16

^[1]

$ 3.95

^[2]

$ 3.92

^[3]

100.00%

$ 0.98

Summary Of Significant Accounting Policies [Line Items]

$ 0.98

Ordinary income

Dividends Treatment For Federal Tax Purposes, Percentage

$ 3.04

$ 3.42

$ 2.90

72.98%

86.60%

73.86%

Capital Gain Income

Summary Of Significant Accounting Policies [Line Items]

Dividends Treatment For Federal Tax Purposes, Percentage

$ 1.12

$ 0.53

$ 0.57

27.02%

13.40%

14.57%

Return of Capital

Summary Of Significant Accounting Policies [Line Items]

Dividends Treatment For Federal Tax Purposes, Percentage

$ 0

$ 0.45

0.00%

11.57%

Dividend Declared

Summary Of Significant Accounting Policies [Line Items]

Dividend Declared | Tax Year 2023

$ 0.98

Summary Of Significant Accounting Policies [Line Items]

Dividend Declared | Tax Year 2024

0.27

Summary Of Significant Accounting Policies [Line Items]

Summary Of Significant Accounting Policies [Line Items]

$ 0.71

Dividend Paid [Member]

Dividend Paid [Member] | Tax Year 2023

$ 0.98

Summary Of Significant Accounting Policies [Line Items]

Dividend Paid [Member] | Tax Year 2022

0.95

Summary Of Significant Accounting Policies [Line Items]

Real estate, at cost (amounts related to variable interest entities (“VIEs”) of $7,054,075 and $6,789,029 at December 31, 2023 and December 31, 2022, respectively)

$ 0.03

[1]	The fourth quarter 2023 regular quarterly dividend was $0.98 per common share, of which approximately $0.27 per common share was allocable to 2023 and approximately $0.71 per common share was allocable to 2024.
[2]	The fourth quarter 2022 regular quarterly dividend was $0.98 per common share, of which approximately $0.03 per common share was allocable to 2022 and approximately $0.95 per common share was allocable to 2023.
[3]	The fourth quarter 2021 regular quarterly dividend was $0.98 per common share, all of which was allocable to 2022.

Consolidated Statements Of Equity - USD ($) $ in Thousands	Total	Common Stock [Member]	Preferred Stock [Member]	Additional Paid-In Capital [Member]	Dividends In Excess Of Earnings [Member]	Treasury Stock, at cost [Member]	Accumulated Other Comprehensive Loss [Member]	Noncontrolling Interests [Member]	Noncontrolling interest - property partnerships [Member]
Equity, shares at Dec. 31, 2020		155,719,000
Equity, value at Dec. 31, 2020	$ 8,339,612	$ 1,557	$ 200,000	$ 6,356,791	$ (509,653)	$ (2,722)	$ (49,890)	$ 616,596	$ 1,726,933
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Redemption of operating partnership units to common stock, shares		524,000
Redemption of operating partnership units to common stock, value	0	$ 5		18,381				(18,386)
Allocated net income for the period	631,932				505,195			55,931	70,806
Dividends declared	(683,843)				(615,021)			(68,822)
Shares issued pursuant to stock purchase plan, shares		9,000
Shares issued pursuant to stock purchase plan, value	1,004			1,004
Net activity from stock option and incentive plan, shares		293,000
Net activity from stock option and incentive plan, value	71,383	$ 3		25,607				45,773
Issuance of operating partnership units for 360 Park Avenue South	99,689							99,689
Preferred Stock, Redeemed	(193,623)		(200,000)	6,377
Preferred Stock Redemption Charge	(6,412)				(6,412)
Proceeds from sale of interest in property partnerships and contributions from noncontrolling interests in property partnerships	18,002								18,002
Non-cash contributions from noncontrolling interest in property partnerhips	0
Distributions to noncontrolling interests in property partnerships	(259,764)								(259,764)
Effective portion of interest rate contracts	8,544						7,703	841
Amortization of interest rate contracts	6,704						5,525	603	576
Reallocation of noncontrolling interest	0			89,570				(89,570)
Equity, shares at Dec. 31, 2021		156,545,000
Equity, value at Dec. 31, 2021	8,033,228	$ 1,565	0	6,497,730	(625,891)	(2,722)	(36,662)	642,655	1,556,553
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Redemption of operating partnership units to common stock, shares		182,000
Redemption of operating partnership units to common stock, value	0	$ 3		6,536				(6,539)
Allocated net income for the period	1,020,584				848,947			96,780	74,857
Dividends declared	(686,126)				(614,412)			(71,714)
Shares issued pursuant to stock purchase plan, shares		10,000
Shares issued pursuant to stock purchase plan, value	1,036			1,036
Net activity from stock option and incentive plan, shares		21,000
Net activity from stock option and incentive plan, value	53,663			7,261				46,402
Issuance of operating partnership units for 360 Park Avenue South	0
Preferred Stock Redemption Charge	0
Proceeds from sale of interest in property partnerships and contributions from noncontrolling interests in property partnerships	849								849
Non-cash contributions from noncontrolling interest in property partnerhips	0
Distributions to noncontrolling interests in property partnerships	(85,518)								(85,518)
Effective portion of interest rate contracts	19,396						17,435	1,961
Amortization of interest rate contracts	6,707						5,509	622	576
Reallocation of noncontrolling interest	$ 0			26,584				(26,584)
Equity, shares at Dec. 31, 2022	156,757,867	156,758,000
Equity, value at Dec. 31, 2022	$ 8,363,819	$ 1,568	0	6,539,147	(391,356)	(2,722)	(13,718)	683,583	1,547,317
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Redemption of operating partnership units to common stock, shares		102,000
Redemption of operating partnership units to common stock, value	0	$ 1		3,793				(3,794)
Allocated net income for the period	291,424				190,215			22,548	78,661
Dividends declared	(688,342)				(615,011)			(73,331)
Shares issued pursuant to stock purchase plan, shares		19,000
Shares issued pursuant to stock purchase plan, value	1,156			1,156
Net activity from stock option and incentive plan, shares		62,000
Net activity from stock option and incentive plan, value	49,060			3,165				45,895
Issuance of operating partnership units for 360 Park Avenue South	0
Preferred Stock Redemption Charge	0
Proceeds from sale of interest in property partnerships and contributions from noncontrolling interests in property partnerships	244,541			160,416					84,125
Non-cash contributions from noncontrolling interest in property partnerhips	17,519
Distributions to noncontrolling interests in property partnerships	(69,975)								(69,975)
Effective portion of interest rate contracts	(14,405)						(12,927)	(1,478)
Amortization of interest rate contracts	6,703						5,498	629	576
Reallocation of noncontrolling interest	$ 0			7,472				(7,472)
Equity, shares at Dec. 31, 2023	156,940,866	156,941,000
Equity, value at Dec. 31, 2023	$ 8,183,981	$ 1,569	$ 0	$ 6,715,149	$ (816,152)	$ (2,722)	$ (21,147)	$ 666,580	$ 1,640,704

Schedule of Finite Lived Intagible Assets Future Amortization Expense (Details) $ in Thousands	Dec. 31, 2023 USD ($)
Acquired Finite-Lived Intangible Assets [Line Items]
2024	$ 52,489
2025	40,739
2026	27,095
2027	20,823
2028	11,113
Above Market Lease Intangibles [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
2024	3,985
2025	1,880
2026	982
2027	743
2028	605
Below Market Lease [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
2024	9,961
2025	9,756
2026	8,602
2027	5,432
2028	$ 2,125

Subsequent Events	12 Months Ended
Subsequent Events	Dec. 31, 2023
Subsequent Events [Abstract]
Subsequent Events	17. Subsequent Events On January 8, 2024, the Company’s completed the acquisition of its joint venture partner’s 50% economic ownership interest in 901 New York Avenue for a gross purchase price of $10.0 million. The acquisition was completed with available cash. 901 New York Avenue is a premier workplace consisting of approximately 548,000 net rentable square feet. The property is subject to existing mortgage indebtedness of approximately $207.1 million. At acquisition the mortgage loan bore interest at 3.61% per annum and matured on January 5, 2025. On January 11, 2024, the Company modified the mortgage loan secured by 901 New York Avenue. The modified mortgage loan continues to bear interest at a fixed rate of 3.61% per annum and has an initial maturity date of January 5, 2025 with two extension options, subject to certain conditions. On January 25, 2024, BXP’s Compensation Committee approved the 2024 Multi-Year Long-Term Incentive Program (the “2024 MYLTIP”) awards under the 2021 Plan to certain executive officers of BXP. The 2024 MYLTIP awards consists of three components. Two of the components, each weighted 40%, utilize BXP’s TSR over a three year measurement period as the performance metrics and the third component utilizes a leverage ratio as the performance metric. Earned awards will range from zero to a maximum of 330,479 LTIP Units depending on BXP’s performance under the three components, with a target of approximately 165,240 LTIP Units. Under ASC 718, the 2024 MYLTIP awards have an aggregate value of approximately $11.1 million. On February 1, 2024, BPLP completed the repayment of $700.0 million in aggregate principal amount of its 3.800% senior notes due February 1, 2024. The repayment was completed with available cash and the $600 million proceeds from the mortgage loan entered into on October 26, 2023 (See Note 7). The repayment price was approximately $713.3 million, which was equal to the stated principal plus approximately $13.3 million of accrued and unpaid interest to, but not including, the repayment date. Excluding the accrued and unpaid interest, the repayment price was equal to the principal amount being repaid. On February 1, 2024, the measurement period for the Company’s 2021 MYLTIP awards ended and, based on BXP’s absolute and relative TSR performance, the final payout was determined to be 112% of target, or an aggregate of approximately $12.6 million (after giving effect to employee separations). As a result, an aggregate of 155,625 2021 MYLTIP Units that had been previously granted were automatically forfeited. On February 2, 2024 and February 6, 2024, BXP issued an aggregate of 71,124 shares of restricted common stock and BPLP issued an aggregate of 429,237 LTIP Units under the 2021 Plan to certain employees of BXP. On February 6, 2024, a joint venture in which the Company owns a 25% interest extended the maturity date of the loan collateralized by its 3 Hudson Boulevard property. At the time of the extension, the loan had an outstanding balance of $80.0 million, bore interest at a variable rate equal to Term SOFR plus approximately 3.61% per annum and was scheduled to mature on February 9, 2024. The extended loan now matures on May 9, 2024 (See Notes 6 and 16). 3 Hudson Boulevard consists of land and improvements held for future development located in New York, New York. On February 9, 2024, a joint venture in which the Company owns a 50% interest exercised an option to extend the maturity date of the construction loan collateralized by its 7750 Wisconsin Avenue property. The construction loan had a total commitment amount of approximately $252.6 million. The extended loan continues to bear interest at a variable rate equal to Term SOFR plus 1.35% per annum and matures on April 26, 2025 (See Note 6). At the time of the extension, the loan had an outstanding balance totaling approximately $251.6 million and was scheduled to mature on April 26, 2024. 7750 Wisconsin Avenue is a premier workplace with approximately 736,000 net rentable square feet located in Bethesda, Maryland.

Consolidated Statement of Capital and Noncontrolling Interests - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Common Stock, Shares, Outstanding	156,940,866	156,757,867
Net activity from stock option and incentive plan, value	$ 49,060	$ 53,663	$ 71,383
Issuance of operating partnership units for 360 Park Avenue South	0	0	99,689
Preferred Stock Redemption Charge	0	0	(6,412)
Effective portion of interest rate contracts	(14,405)	19,396	8,544
Amortization of interest rate contracts	6,703	6,707	6,704
Proceeds from sale of interest in property partnerships and contributions from noncontrolling interests in property partnerships	244,541	849	18,002
Non-cash contributions from noncontrolling interest in property partnerhips	17,519	0	0
Distributions to noncontrolling interests in property partnerships	$ (69,975)	$ (85,518)	$ (259,764)
General Partner [Member]
Common Stock, Shares, Outstanding	1,755,000	1,750,000	1,746,000	1,731,000
Net activity from contributions and unearned compensation	5,000	1,000	5,000
Conversion of redeemable partnership units	0	3,000	10,000
Limited Partner [Member]
Common Stock, Shares, Outstanding	155,185,000	155,008,000	154,799,000	153,988,000
Net activity from contributions and unearned compensation	75,000	30,000	295,000
Conversion of redeemable partnership units	102,000	179,000	516,000
Partners' Capital (General and Limited Partners)[Member]
Beginning Balance	$ 4,973,951	$ 5,299,428	$ 4,173,290	$ 4,554,639
Net activity from contributions and unearned compensation, value	4,321	8,291	26,614
Allocated net income for the period	197,223	860,485	512,474
Distributions	(615,011)	(614,412)	(612,461)
Preferred Stock Redemption Charge			(6,412)
Conversion of redeemable partnership units, value	3,794	6,539	18,386
Adjustment to reflect redeemable partnership units at redemption value	(76,220)	865,235	(319,950)
Proceeds from sale of interest in property partnerships and contributions from noncontrolling interests in property partnerships	160,416
Preferred Units [Member]
Beginning Balance	0	0	0	193,623
Allocated net income for the period			2,560
Distributions			(2,560)
Preferred Stock, Redemption Amount			(193,623)
Accumulated Other Comprehensive Loss [Member]
Beginning Balance	(21,147)	(13,718)	(36,662)	(49,890)
Effective portion of interest rate contracts	(12,927)	17,435	7,703
Amortization of interest rate contracts	5,498	5,509	5,525
Noncontrolling interest - property partnerships [Member]
Beginning Balance	1,640,704	1,547,317	1,556,553	1,726,933
Allocated net income for the period	78,661	74,857	70,806
Amortization of interest rate contracts	576	576	576
Proceeds from sale of interest in property partnerships and contributions from noncontrolling interests in property partnerships	84,125	849	18,002
Distributions to noncontrolling interests in property partnerships	(69,975)	(85,518)	(259,764)
Total Capital [Member]
Beginning Balance	6,593,508	6,833,027	5,693,181	6,425,305
Net activity from contributions and unearned compensation, value	4,321	8,291	26,614
Allocated net income for the period	275,884	935,342	585,840
Distributions	(615,011)	(614,412)	(615,021)
Preferred Stock, Redemption Amount			(193,623)
Preferred Stock Redemption Charge			(6,412)
Conversion of redeemable partnership units, value	3,794	6,539	18,386
Adjustment to reflect redeemable partnership units at redemption value	(76,220)	865,235	(319,950)
Effective portion of interest rate contracts	(12,927)	17,435	7,703
Amortization of interest rate contracts	6,074	6,085	6,101
Proceeds from sale of interest in property partnerships and contributions from noncontrolling interests in property partnerships	244,541	849	18,002
Distributions to noncontrolling interests in property partnerships	(69,975)	(85,518)	(259,764)
Noncontrolling interest - Redeemable partnership units [Member]
Beginning Balance	1,347,575	1,280,886	2,078,603	$ 1,643,024
Net activity from contributions and unearned compensation, value	45,895	46,408	45,773
Allocated net income for the period	22,548	96,780	55,931
Distributions	(73,331)	(71,714)	(68,822)
Issuance of operating partnership units for 360 Park Avenue South			99,689
Conversion of redeemable partnership units, value	(3,794)	(6,539)	(18,386)
Adjustment to reflect redeemable partnership units at redemption value	76,220	(865,235)	319,950
Effective portion of interest rate contracts	(1,478)	1,961	841
Amortization of interest rate contracts	$ 629	$ 622	$ 603

Consolidated Balance Sheets (Parenthetical) - USD ($)
$ in Thousands

Dec. 31, 2023

Dec. 31, 2022

$ 26,749,209

$ 25,389,663

Right of use assets - finance leases (amounts related to VIEs of $21,000 and $21,000 at December 31, 2023 and December 31, 2022, respectively)

401,680

237,510

Right of use assets - operating leases (amounts related to VIEs of $158,885 and $0 at December 31, 2023 and December 31, 2022, respectively)

^[1]

324,298

167,351

Less: accumulated depreciation (amounts related to VIEs of $(1,501,483) and $(1,381,401) at December 31, 2023 and December 31, 2022, respectively)

(6,881,728)

(6,298,082)

Cash and cash equivalents (amounts related to VIEs of $245,317 and $259,658 at December 31, 2023 and December 31, 2022, respectively)

1,531,477

690,333

Cash held in escrows (amounts related to VIEs of $22,160 and $0 at December 31, 2023 and December 31, 2022, respectively)

81,090

46,479

Tenant and other receivables, net (amounts related to VIEs of $27,987 and $16,521 at December 31, 2023 and December 31, 2022, respectively)

122,407

81,389

Accrued rental income, net (amounts related to VIEs of $401,159 and $367,138 at December 31, 2023 and December 31, 2022, respectively)

1,355,212

1,276,580

Deferred charges, net (amounts related to VIEs of $175,383 and $176,597 at December 31, 2023 and December 31, 2022, respectively)

760,421

733,282

Prepaid expenses and other assets (amounts related to VIEs of $11,824 and $11,647 at December 31, 2023 and December 31, 2022, respectively)

64,230

43,589

Mortgage notes payable, net (amounts related to VIEs of $3,277,185 and $3,272,368 at December 31, 2023 and December 31, 2022, respectively)

4,166,379

3,272,368

Lease liabilities - finance leases (amounts related to VIEs of $20,794 and $20,604 at December 31, 2023 and December 31, 2022, respectively)

417,961

249,335

Lease liabilities - operating leases (amounts related to VIEs of $145,826 and $0 at December 31, 2023 and December 31, 2022, respectively)

350,391

204,686

Accounts payable and accrued expenses (amounts related to VIEs of $59,667 and $29,466 at December 31, 2023 and December 31, 2022, respectively)

458,329

417,545

Other liabilities (amounts related to VIEs of $115,275 and $114,232 at December 31, 2023 and December 31, 2022, respectively)

$ 445,947

$ 450,918

Reedemable deferred stock units, units

119,471

97,853

Limited Partners' Capital Account, Units Outstanding (in units)

155,185,716

General Partners' Capital Account, Units Outstanding (in units)

1,755,150

Excess stock, par value

$ 0.01

Excess stock, shares authorized

150,000,000

Excess stock, shares outstanding

Excess stock, shares issued

Preferred stock, par value

$ 0.01

Preferred stock, shares authorized

50,000,000

Preferred stock / units, shares / units issued (in shares / units)

Preferred stock / units, shares / units outstanding (in shares / units)

Common Stock, Par or Stated Value Per Share

$ 0.01

Common stock, shares authorized

250,000,000

Common stock, shares issued

157,019,766

156,836,767

Common Stock, Shares, Outstanding

156,940,866

156,757,867

Treasury common stock at cost, shares

78,900

Real estate, at cost (amounts related to variable interest entities (“VIEs”) of $7,054,075 and $6,789,029 at December 31, 2023 and December 31, 2022, respectively)

$ 26,382,944

$ 25,022,149

Right of use assets - finance leases (amounts related to VIEs of $21,000 and $21,000 at December 31, 2023 and December 31, 2022, respectively)

401,680

237,510

Right of use assets - operating leases (amounts related to VIEs of $158,885 and $0 at December 31, 2023 and December 31, 2022, respectively)

^[1]

324,298

167,351

Less: accumulated depreciation (amounts related to VIEs of $(1,501,483) and $(1,381,401) at December 31, 2023 and December 31, 2022, respectively)

(6,758,361)

(6,180,474)

Cash and cash equivalents (amounts related to VIEs of $245,317 and $259,658 at December 31, 2023 and December 31, 2022, respectively)

1,531,477

690,333

Cash held in escrows (amounts related to VIEs of $22,160 and $0 at December 31, 2023 and December 31, 2022, respectively)

81,090

46,479

Tenant and other receivables, net (amounts related to VIEs of $27,987 and $16,521 at December 31, 2023 and December 31, 2022, respectively)

122,407

81,389

Accrued rental income, net (amounts related to VIEs of $401,159 and $367,138 at December 31, 2023 and December 31, 2022, respectively)

1,355,212

1,276,580

Deferred charges, net (amounts related to VIEs of $175,383 and $176,597 at December 31, 2023 and December 31, 2022, respectively)

760,421

733,282

Prepaid expenses and other assets (amounts related to VIEs of $11,824 and $11,647 at December 31, 2023 and December 31, 2022, respectively)

64,230

43,589

Mortgage notes payable, net (amounts related to VIEs of $3,277,185 and $3,272,368 at December 31, 2023 and December 31, 2022, respectively)

4,166,379

3,272,368

Lease liabilities - finance leases (amounts related to VIEs of $20,794 and $20,604 at December 31, 2023 and December 31, 2022, respectively)

417,961

249,335

Lease liabilities - operating leases (amounts related to VIEs of $145,826 and $0 at December 31, 2023 and December 31, 2022, respectively)

350,391

204,686

Accounts payable and accrued expenses (amounts related to VIEs of $59,667 and $29,466 at December 31, 2023 and December 31, 2022, respectively)

458,329

417,545

Other liabilities (amounts related to VIEs of $115,275 and $114,232 at December 31, 2023 and December 31, 2022, respectively)

$ 445,947

$ 450,918

Reedemable deferred stock units, units

119,471

97,853

Limited Partners' Capital Account, Units Outstanding (in units)

155,185,716

155,008,185

General Partners' Capital Account, Units Outstanding (in units)

1,755,150

1,749,682

NonControlling Interest Redeemable Partnership Units Common Units Shares Outstanding

16,508,277

16,531,172

NonControlling Interest Redeemable Partnership Units Common Units Long Term Incentive Units At Redemption Value Shares Outstanding

2,065,861

1,679,175

Variable Interest Entity, Primary Beneficiary [Member]

Real estate, at cost (amounts related to variable interest entities (“VIEs”) of $7,054,075 and $6,789,029 at December 31, 2023 and December 31, 2022, respectively)

$ 7,054,075

$ 6,789,029

Right of use assets - finance leases (amounts related to VIEs of $21,000 and $21,000 at December 31, 2023 and December 31, 2022, respectively)

21,000

Right of use assets - operating leases (amounts related to VIEs of $158,885 and $0 at December 31, 2023 and December 31, 2022, respectively)

158,885

Less: accumulated depreciation (amounts related to VIEs of $(1,501,483) and $(1,381,401) at December 31, 2023 and December 31, 2022, respectively)

(1,501,483)

(1,381,401)

Cash and cash equivalents (amounts related to VIEs of $245,317 and $259,658 at December 31, 2023 and December 31, 2022, respectively)

245,317

259,658

Cash held in escrows (amounts related to VIEs of $22,160 and $0 at December 31, 2023 and December 31, 2022, respectively)

22,160

Tenant and other receivables, net (amounts related to VIEs of $27,987 and $16,521 at December 31, 2023 and December 31, 2022, respectively)

27,987

16,521

Accrued rental income, net (amounts related to VIEs of $401,159 and $367,138 at December 31, 2023 and December 31, 2022, respectively)

401,159

367,138

Deferred charges, net (amounts related to VIEs of $175,383 and $176,597 at December 31, 2023 and December 31, 2022, respectively)

175,383

176,597

Prepaid expenses and other assets (amounts related to VIEs of $11,824 and $11,647 at December 31, 2023 and December 31, 2022, respectively)

11,824

11,647

Mortgage notes payable, net (amounts related to VIEs of $3,277,185 and $3,272,368 at December 31, 2023 and December 31, 2022, respectively)

3,277,185

3,272,368

Lease liabilities - finance leases (amounts related to VIEs of $20,794 and $20,604 at December 31, 2023 and December 31, 2022, respectively)

20,794

20,604

Lease liabilities - operating leases (amounts related to VIEs of $145,826 and $0 at December 31, 2023 and December 31, 2022, respectively)

145,826

Accounts payable and accrued expenses (amounts related to VIEs of $59,667 and $29,466 at December 31, 2023 and December 31, 2022, respectively)

59,667

29,466

Other liabilities (amounts related to VIEs of $115,275 and $114,232 at December 31, 2023 and December 31, 2022, respectively)

115,275

114,232

Variable Interest Entity, Primary Beneficiary [Member] | Boston Properties Limited Partnership

Real estate, at cost (amounts related to variable interest entities (“VIEs”) of $7,054,075 and $6,789,029 at December 31, 2023 and December 31, 2022, respectively)

7,054,075

6,789,029

Right of use assets - finance leases (amounts related to VIEs of $21,000 and $21,000 at December 31, 2023 and December 31, 2022, respectively)

21,000

Right of use assets - operating leases (amounts related to VIEs of $158,885 and $0 at December 31, 2023 and December 31, 2022, respectively)

158,885

Less: accumulated depreciation (amounts related to VIEs of $(1,501,483) and $(1,381,401) at December 31, 2023 and December 31, 2022, respectively)

(1,501,483)

(1,381,401)

Cash and cash equivalents (amounts related to VIEs of $245,317 and $259,658 at December 31, 2023 and December 31, 2022, respectively)

245,317

259,658

Cash held in escrows (amounts related to VIEs of $22,160 and $0 at December 31, 2023 and December 31, 2022, respectively)

22,160

Tenant and other receivables, net (amounts related to VIEs of $27,987 and $16,521 at December 31, 2023 and December 31, 2022, respectively)

27,987

16,521

Accrued rental income, net (amounts related to VIEs of $401,159 and $367,138 at December 31, 2023 and December 31, 2022, respectively)

401,159

367,138

Deferred charges, net (amounts related to VIEs of $175,383 and $176,597 at December 31, 2023 and December 31, 2022, respectively)

175,383

176,597

Prepaid expenses and other assets (amounts related to VIEs of $11,824 and $11,647 at December 31, 2023 and December 31, 2022, respectively)

11,824

11,647

Mortgage notes payable, net (amounts related to VIEs of $3,277,185 and $3,272,368 at December 31, 2023 and December 31, 2022, respectively)

3,277,185

3,272,368

Lease liabilities - finance leases (amounts related to VIEs of $20,794 and $20,604 at December 31, 2023 and December 31, 2022, respectively)

20,794

20,604

Lease liabilities - operating leases (amounts related to VIEs of $145,826 and $0 at December 31, 2023 and December 31, 2022, respectively)

145,826

Accounts payable and accrued expenses (amounts related to VIEs of $59,667 and $29,466 at December 31, 2023 and December 31, 2022, respectively)

59,667

29,466

Other liabilities (amounts related to VIEs of $115,275 and $114,232 at December 31, 2023 and December 31, 2022, respectively)

$ 115,275

$ 114,232

[1]	See Note 4.

Commitments And Contingencies (Details) $ in Thousands	12 Months Ended
Commitments And Contingencies (Details) $ in Thousands	Dec. 31, 2023 USD ($) ft² Real_Estate_Properties	Oct. 02, 2023 USD ($)	Sep. 13, 2023 USD ($)	Dec. 31, 2022 USD ($)
Commitments And Contingencies [Line Items]
Letter of credit and performance obligations	$ 21,600
Note receivable, net	1,714			$ 0
Property insurance program per occurrence limits	1,000,000
Per occurrence limit for NBCR Coverage	1,000,000
Value of program trigger	$ 200,000
Coinsurance of program trigger	20.00%
Program trigger deductible	20.00%
Per occurrence limit of the earthquake insurance which covers San Francisco and Los Angeles regions	$ 330,000
Annual aggregate limit of the earthquake insurance which covers San Francisco and Los Angeles regions	330,000
Amount of earthquake insurance provided by IXP, LLC as direct insurer San Francisco and Los Angeles	$ 30,000
Deductible in insurance as a percentage of the value of the affected property, San Francisco and Los Angeles	5.00%
Per Occurrence Limit of Earthquake Insurance Seattle	$ 110,000
Annual Aggregate Limit of Earthquake Insurance Seattle	$ 110,000
Earthquake Deductible Insurance Percentage of Value of the Affected Property Seattle	2.00%
Accrued Liabilities	$ 1,500
Loss Contingency, Portion Not Accrued	31,000
Boston Properties Limited Partnership
Commitments And Contingencies [Line Items]
Note receivable, net	1,714			$ 0
Operating partnership guarantee to cover liabilities of IXP	20,000
767 Venture, LLC [Member]
Commitments And Contingencies [Line Items]
Maximum funding obligation	8,500
Property insurance program per occurrence limits	1,625,000
601 Lexington Avenue
Commitments And Contingencies [Line Items]
Coverage For Acts Of Terrorism Under TRIA Covered in Excess of Amount Covered by IXP	1,350,000
Coverage For Acts Of Terrorism Under TRIA Covered in Excess of Amount Covered by IXP - Property and Terrorism	750,000
Coverage For Acts Of Terrorism Under TRIA Covered in Excess of Amount Covered by IXP - Terrorism	600,000
Sum of Coverage Covered by IXP and Excess Coverage for Property and Terrorism	1,750,000
Metropolitan Square \| Affiliated Entity
Commitments And Contingencies [Line Items]
Note receivable, net	$ 1,700
Metropolitan Square \| Subordinated Debt
Commitments And Contingencies [Line Items]
Debt Instrument, Unused Borrowing Capacity, Amount		$ 100,000
Debt Instrument, Interest Rate, Stated Percentage			12.00%
Metropolitan Square \| Scenario, Plan
Commitments And Contingencies [Line Items]
Debt Instrument, Unused Borrowing Capacity, Amount			$ 100,000
Metropolitan Square \| Scenario, Plan \| Affiliated Entity
Commitments And Contingencies [Line Items]
Loans and Leases Receivable, Loans in Process			$ 20,000
Metropolitan Square \| Scenario, Plan \| Subordinated Debt \| Affiliated Entity
Commitments And Contingencies [Line Items]
Percent of Total		20.00%
Loans and Leases Receivable, Loans in Process		$ 20,000
Residential Properties [Member] \| Scenario, Plan
Commitments And Contingencies [Line Items]
Net Rentable Area (in sf) \| ft²	400,000
Office and Life Sciences Building [Member]
Commitments And Contingencies [Line Items]
Number of real estate properties \| Real_Estate_Properties	167
Office and Life Sciences Building [Member] \| Scenario, Plan
Commitments And Contingencies [Line Items]
Net Rentable Area (in sf) \| ft²	1,100,000
Number of real estate properties	2

Pay vs Performance Disclosure - USD ($) $ in Thousands	12 Months Ended
Pay vs Performance Disclosure - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Pay vs Performance Disclosure
Net Income (Loss) Attributable to Parent	$ 190,215	$ 848,947	$ 505,195

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

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Investments In Unconsolidated Joint Ventures [Abstract]

Consolidated Statements Of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Net income (loss)	$ 291,424	$ 1,020,584	$ 631,932
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	830,813	749,775	717,336
Amortization of right of use assets - operating leases	1,940	2,427	3,516
Non-cash compensation expense	51,478	52,026	50,860
Loss (income) from unconsolidated joint ventures	239,543	59,840	2,570
Distributions of net cash flow from operations of unconsolidated joint ventures	24,637	26,827	21,542
Losses (gains) from investments in securities	(5,556)	6,453	(5,626)
Allowance for current expected credit losses (gains)	373	(224)	(1,207)
Non-cash portion of interest expense	30,523	25,831	23,368
Settlement of accreted debt discount on redemption of unsecured senior notes	0	0	(8,500)
Losses from early extinguishment of debt	0	0	45,182
Other Income - assignment fee	0	(6,624)	0
Gains on sales of real estate	(517)	(437,019)	(123,660)
Gain on sales-type lease	0	(10,058)	0
Unrealized Gain (Loss) on non-real estate Investments	(239)	150	0
Change in assets and liabilities:
Tenant and other receivables, net	(31,470)	(7,621)	4,820
Notes receivable, net	0	(152)	(545)
Accrued rental income, net	(99,539)	(98,075)	(101,548)
Prepaid expenses and other assets	(7,336)	20,099	(20,811)
Right of use assets - operating lease	(25,640)	0	0
Lease liabilities - operating leases	(121)	125	(23,599)
Accounts payable and accrued expenses	41,696	(22,777)	20,025
Accrued interest payable	29,910	8,989	(10,839)
Other liabilities	7,267	(24,120)	(28,739)
Tenant leasing costs	(77,666)	(84,057)	(62,850)
Total adjustments	1,010,096	261,815	501,295
Net cash provided by operating activities	1,301,520	1,282,399	1,133,227
Cash flows from investing activities:
Acquisitions of real estate	0	(1,320,273)	(222,260)
Construction in progress	(525,963)	(500,273)	(513,878)
Building and other capital improvements	(171,424)	(177,004)	(150,998)
Tenant improvements	(310,925)	(218,685)	(263,952)
Proceeds from sales of real estate	517	834,770	179,887
Acquisition of real estate (net of cash received upon consolidation)	(13,155)	0	0
Proceeds from assignment fee	0	6,624	0
Capital contributions to unconsolidated joint ventures	(192,650)	(277,581)	(98,152)
Capital distributions from unconsolidated joint ventures	32,787	37,122	122
Proceeds from Sale of Equity Method Investments	0	0	17,789
Investment in non-real estate investments	(2,187)	(2,404)	0
Issuance of note receivables (including related party)	(12,177)	0	0
Proceeds from note receivable	0	10,000	10,035
Investments in securities, net	1,496	4,902	1,451
Net cash used in investing activities	(1,193,681)	(1,602,802)	(1,039,956)
Cash flows from financing activities:
Proceeds from Secured Notes Payable	600,000	0	1,201,388
Repayments of mortgage notes payable	0	0	(832,296)
Proceeds from unsecured senior notes	747,727	749,557	1,695,996
Redemption of unsecured senior notes	(500,000)	0	(1,841,500)
Borrowings on unsecured line of credit	0	985,000	770,000
Repayments of unsecured line of credit	0	(1,130,000)	(625,000)
Borrowings on unsecured term loan	1,200,000	730,000	0
Redemption of preferred stock	0	0	(200,000)
Payments on finance lease obligations	0	0	1,250
Repayment of unsecured term loan	(730,000)	0	(500,000)
Deferred financing costs	(19,416)	(8,460)	(20,757)
Debt Issuance Costs	0	0	(16,186)
Debt prepayment and extinguishment costs	0	0	(43,036)
Net activity from equity transactions	367	(352)	24,214
Dividends and distributions	(687,809)	(685,019)	(683,753)
Proceeds from sale of interest in property partnerships and contributions from noncontrolling interests in property partnerships	244,541	849	18,002
Distributions to noncontrolling interests in property partnerships	(69,975)	(85,518)	(259,764)
Net cash provided by (used in) financing activities	767,916	556,057	(1,311,442)
Net increase (decrease) in cash and cash equivalents and cash held in escrows	875,755	235,654	(1,218,171)
Cash and cash equivalents and cash held in escrows, beginning of period	736,812	501,158	1,719,329
Cash and cash equivalents and cash held in escrows, end of period	1,612,567	736,812	501,158
Reconciliation of cash and cash equivalents and cash held in escrow
Cash and cash equivalents, beginning of period	690,333	452,692	1,668,742
Cash held in escrows, beginning of period	46,479	48,466	50,587
Cash and cash equivalents, end of period	1,531,477	690,333	452,692
Cash held in escrows,end of period	81,090	46,479	48,466
Supplemental disclosures:
Cash paid for interest	553,989	449,903	465,442
Interest capitalized	42,633	52,130	53,097
Non-cash investing and financing activities:
Write-off of fully depreciated real estate	(135,093)	(119,534)	(239,317)
Change in real estate included in accounts payable and accrued expenses	3,668	97,586	(25,183)
Right-of-Use Asset Obtained in Exchange for Operating Lease Liability	141,179	0	26,887
Right-of-Use Asset Obtained in Exchange for Finance Lease Liability	163,056	0	0
Non-cash contributions from noncontrolling interest in property partnerhips	17,519	0	0
Capitalized operating lease costs	12,580	0	0
Construction in progress from prepaid expenses and other assets	25,577	0	0
Investment in unconsolidated joint ventures eliminated upon consolidation	183,817	0	0
Mortgage notes payable recorded upon consolidation	300,000	0	0
Real estate and intangibles recorded upon consolidation	(490,720)	0	0
Interest rate swaps recorded upon consolidation	(7,337)	0	0
Construction in progress, net deconsolidated	0	(11,316)	(299,947)
Investment in unconsolidated joint ventures recorded upon deconsolidation	0	11,316	107,132
Sales-type lease origination	0	13,045	0
Derecognition of assets in exchange for sales-type lease obligation	0	(2,987)	0
Prepaid expenses and other assets, net deconsolidated	0	0	(5,011)
Assumption of mortgage notes payable	0	0	200,311
Mortgage notes payable, net deconsolidation	0	0	(198,381)
Issuance of operating partnership units	0	0	99,689
Dividends and distributions declared but not paid	171,176	170,643	169,859
Conversions of noncontrolling interests to stockholders’ equity	3,794	6,539	18,386
Issuance of restricted securities to employees and non-employee directors	48,141	48,417	44,405
Cash
Cash flows from financing activities:
Proceeds from sale of interest in property partnerships and contributions from noncontrolling interests in property partnerships	227,022	849	18,002
Boston Properties Limited Partnership
Net income (loss)	298,432	1,032,122	641,771
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	823,805	742,293	709,035
Amortization of right of use assets - operating leases	1,940	2,427	3,516
Non-cash compensation expense	51,478	52,026	50,860
Loss (income) from unconsolidated joint ventures	239,543	59,840	2,570
Distributions of net cash flow from operations of unconsolidated joint ventures	24,637	26,827	21,542
Losses (gains) from investments in securities	(5,556)	6,453	(5,626)
Allowance for current expected credit losses (gains)	373	(224)	(1,207)
Non-cash portion of interest expense	30,523	25,831	23,368
Settlement of accreted debt discount on redemption of unsecured senior notes	0	0	(8,500)
Losses from early extinguishment of debt	0	0	45,182
Other Income - assignment fee	0	(6,624)	0
Gains on sales of real estate	(517)	(441,075)	(125,198)
Gain on sales-type lease	0	(10,058)	0
Unrealized Gain (Loss) on non-real estate Investments	(239)	150	0
Change in assets and liabilities:
Tenant and other receivables, net	(31,470)	(7,621)	4,820
Notes receivable, net	0	(152)	(545)
Accrued rental income, net	(99,539)	(98,075)	(101,548)
Prepaid expenses and other assets	(7,336)	20,099	(20,811)
Right of use assets - operating lease	(25,640)	0	0
Lease liabilities - operating leases	(121)	125	(23,599)
Accounts payable and accrued expenses	41,696	(22,777)	20,025
Accrued interest payable	29,910	8,989	(10,839)
Other liabilities	7,267	(24,120)	(28,739)
Tenant leasing costs	(77,666)	(84,057)	(62,850)
Total adjustments	1,003,088	250,277	491,456
Net cash provided by operating activities	1,301,520	1,282,399	1,133,227
Cash flows from investing activities:
Acquisitions of real estate	0	(1,320,273)	(222,260)
Construction in progress	(525,963)	(500,273)	(513,878)
Building and other capital improvements	(171,424)	(177,004)	(150,998)
Tenant improvements	(310,925)	(218,685)	(263,952)
Proceeds from sales of real estate	517	834,770	179,887
Acquisition of real estate (net of cash received upon consolidation)	(13,155)	0	0
Proceeds from assignment fee	0	6,624	0
Capital contributions to unconsolidated joint ventures	(192,650)	(277,581)	(98,152)
Capital distributions from unconsolidated joint ventures	32,787	37,122	122
Proceeds from Sale of Equity Method Investments	0	0	17,789
Investment in non-real estate investments	(2,187)	(2,404)	0
Issuance of note receivables (including related party)	(12,177)	0	0
Proceeds from note receivable	0	10,000	10,035
Investments in securities, net	1,496	4,902	1,451
Net cash used in investing activities	(1,193,681)	(1,602,802)	(1,039,956)
Cash flows from financing activities:
Proceeds from Secured Notes Payable	600,000	0	1,201,388
Repayments of mortgage notes payable	0	0	(832,296)
Proceeds from unsecured senior notes	747,727	749,557	1,695,996
Redemption of unsecured senior notes	(500,000)	0	(1,841,500)
Borrowings on unsecured line of credit	0	985,000	770,000
Repayments of unsecured line of credit	0	(1,130,000)	(625,000)
Borrowings on unsecured term loan	1,200,000	730,000	0
Redemption of preferred stock	0	0	(200,000)
Payments on finance lease obligations	0	0	1,250
Repayment of unsecured term loan	(730,000)	0	(500,000)
Deferred financing costs	(19,416)	(8,460)	(20,757)
Debt Issuance Costs	0	0	(16,186)
Debt prepayment and extinguishment costs	0	0	(43,036)
Net activity from equity transactions	367	(352)	24,214
Dividends and distributions	(687,809)	(685,019)	(683,753)
Distributions to noncontrolling interests in property partnerships	(69,975)	(85,518)	(259,764)
Net cash provided by (used in) financing activities	767,916	556,057	(1,311,442)
Net increase (decrease) in cash and cash equivalents and cash held in escrows	875,755	235,654	(1,218,171)
Cash and cash equivalents and cash held in escrows, beginning of period	736,812	501,158	1,719,329
Cash and cash equivalents and cash held in escrows, end of period	1,612,567	736,812	501,158
Reconciliation of cash and cash equivalents and cash held in escrow
Cash and cash equivalents, beginning of period	690,333	452,692	1,668,742
Cash held in escrows, beginning of period	46,479	48,466	50,587
Cash and cash equivalents, end of period	1,531,477	690,333	452,692
Cash held in escrows,end of period	81,090	46,479	48,466
Supplemental disclosures:
Cash paid for interest	553,989	449,903	465,442
Interest capitalized	42,633	52,130	53,097
Non-cash investing and financing activities:
Write-off of fully depreciated real estate	(133,844)	(119,534)	(238,003)
Change in real estate included in accounts payable and accrued expenses	3,668	97,586	(25,183)
Right-of-Use Asset Obtained in Exchange for Operating Lease Liability	141,179	0	26,887
Right-of-Use Asset Obtained in Exchange for Finance Lease Liability	163,056	0	0
Non-cash contributions from noncontrolling interest in property partnerhips	17,519	0	0
Capitalized operating lease costs	12,580	0	0
Construction in progress from prepaid expenses and other assets	25,577	0	0
Investment in unconsolidated joint ventures eliminated upon consolidation	183,817	0	0
Mortgage notes payable recorded upon consolidation	300,000	0	0
Real estate and intangibles recorded upon consolidation	(490,720)	0	0
Interest rate swaps recorded upon consolidation	(7,337)	0	0
Construction in progress, net deconsolidated	0	(11,316)	(299,947)
Investment in unconsolidated joint ventures recorded upon deconsolidation	0	11,316	107,132
Sales-type lease origination	0	13,045	0
Derecognition of assets in exchange for sales-type lease obligation	0	(2,987)	0
Prepaid expenses and other assets, net deconsolidated	0	0	(5,011)
Assumption of mortgage notes payable	0	0	200,311
Mortgage notes payable, net deconsolidation	0	0	(198,381)
Issuance of operating partnership units	0	0	99,689
Dividends and distributions declared but not paid	171,176	170,643	169,859
Conversions of noncontrolling interests to stockholders’ equity	3,794	6,539	18,386
Issuance of restricted securities to employees and non-employee directors	48,141	48,417	44,405
Boston Properties Limited Partnership \| Cash
Cash flows from financing activities:
Proceeds from sale of interest in property partnerships and contributions from noncontrolling interests in property partnerships	$ 227,022	$ 849	$ 18,002

Sales Type Lease Maturity Schedule Prior Year (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Sales-Type and Direct Financing Leases, Lease Receivable, Payments to be Received, Fiscal Year Maturity [Abstract]
2023	$ 31	$ 0
2024	124	31
2025	372	124
2026	756	372
2027	775	756
Thereafter	267,474	268,249
Total lease payments to be received	269,532	269,532
Interest portion	255,579	256,504
Sales-type lease receivable, net	13,953	13,028
Sales-type Lease, Unguaranteed Residual Asset	18	17
Current expected credit loss adjustment	(267)	(234)
Sales-type lease receivable, net	$ 13,704	$ 12,811

Investments in Unconsolidated Joint Ventures

12 Months Ended

Dec. 31, 2023

Investments In Unconsolidated Joint Ventures

6. Investments in Unconsolidated Joint Ventures

The investments in unconsolidated joint ventures consist of the following at December 31, 2023 and December 31, 2022:


					Carrying Value of Investment (1)
Entity	Properties	Nominal % Ownership			December 31, 2023		December 31, 2022
					(in thousands)
Square 407 Limited Partnership	Market Square North	50.00	%		$	(5,996)	$	(6,198)
BP/CRF Metropolitan Square LLC	Metropolitan Square	20.00	%	(2)	—		(37,629)
901 New York, LLC	901 New York Avenue	25.00	%	(3)	(11,764)		(12,493)
WP Project Developer LLC	Wisconsin Place Land and Infrastructure	33.33	%	(4)	30,375		31,971
500 North Capitol Venture LLC	500 North Capitol Street, NW	30.00	%		(10,253)		(9,185)
501 K Street LLC	1001 6th Street	50.00	%		44,774		42,922
Podium Developer LLC	The Hub on Causeway - Podium	50.00	%		45,201		46,839
Residential Tower Developer LLC	Hub50House	50.00	%		40,235		45,414
Hotel Tower Developer LLC	The Hub on Causeway - Hotel Air Rights	50.00	%		13,494		12,366
Office Tower Developer LLC	100 Causeway Street	50.00	%		57,660		59,716
1265 Main Office JV LLC	1265 Main Street	50.00	%		3,585		3,465
BNY Tower Holdings LLC	Dock 72	50.00	%	(5)	(11,890)		(19,921)

CA-Colorado Center, LLC	Colorado Center	50.00	%		237,815		233,862
7750 Wisconsin Avenue LLC	7750 Wisconsin Avenue	50.00	%		50,064		52,152
BP-M 3HB Venture LLC	3 Hudson Boulevard	25.00	%		115,103		116,397
SMBP Venture LP	Santa Monica Business Park	55.00	%	(6)	—		164,735
Platform 16 Holdings LP	Platform 16	55.00	%	(7)(8)	45,564		158,109
Gateway Portfolio Holdings LLC	Gateway Commons	50.00	%		376,834		324,038
Rosecrans-Sepulveda Partners 4, LLC	Beach Cities Media Campus	50.00	%		27,034		27,000
Safeco Plaza REIT LLC	Safeco Plaza	33.67	%	(8)(9)	44,734		69,785
360 PAS Holdco LLC	360 Park Avenue South	71.11	%	(8)(10)	42,988		114,992
PR II/BXP Reston Gateway LLC	Skymark - Reston Next Residential	20.00	%		15,184		11,351
751 Gateway Holdings LLC	751 Gateway	49.00	%		93,411		80,714
200 Fifth Avenue JV LLC	200 Fifth Avenue	26.69	%	(8)	75,718		120,083
ABXP Worldgate Investments LLC	13100 and 13150 Worldgate Drive	50.00	%		17,546		N/A
					$	1,337,416	$	1,630,485

_______________

(1)Investments with deficit balances aggregating approximately $39.9 million and $85.4 million at December 31, 2023 and December 31, 2022, respectively, are included within Other Liabilities in the Company’s Consolidated Balance Sheets.

(2)During the year ended December 31, 2023, the Company completed a restructuring of its ownership in Metropolitan Square, as described below in this Note 6.

(3)The Company’s economic ownership increased based on the achievement of certain return thresholds. At December 31, 2023 and December 31, 2022, the Company’s economic ownership was approximately 50%. On January 8, 2024, the Company’s joint venture partner transferred all of its interest in the joint venture to the Company for a gross purchase price of $10.0 million, see Note 17 for more information.

(4)The Company’s wholly-owned subsidiary that owns Wisconsin Place Office also owns a 33.33% interest in the joint venture entity that owns the land, parking garage and infrastructure of the project.

(5)This property includes net equity balances from the amenity joint venture.

(6)During the year ended December 31, 2023, the Company completed the acquisition of its joint venture partner’s 45% ownership interest in Santa Monica Business Park, as described below in this Note 6 and Note 3.

(7)At December 31, 2022, this entity was a VIE.

(8)During the year ended December 31, 2023, the Company recognized an other-than-temporary impairment loss on its investment.

(9)The Company’s ownership includes (1) a 33.0% direct interest in the joint venture, and (2) an additional 1% interest in each of the two entities through which each partner owns its interest in the joint venture.

(10)On December 14, 2023, the Company completed the acquisition of all of one of its joint venture partners ownership interest. As a result of this acquisition, at December 31, 2023, the Company’s ownership includes (1) a 35.79% direct interest in the joint venture, (2) an additional 35.02% indirect ownership in the joint venture, and (3) an additional 1% interest in the entity through which the partner owns its interest in the joint venture. The Company’s partner will fund required capital until its aggregate investment is approximately 29% of all capital contributions; thereafter, the partners will fund required capital according to their percentage interests. At December 31, 2022, the Company’s ownership included (1) a 35.79% direct interest in the joint venture, (2) an additional 5.837% indirect ownership in the joint venture, and (3) an additional 1% interest in each of the two entities through which each partner owns its interest in the joint venture.

Certain of the Company’s unconsolidated joint venture agreements include provisions whereby, at certain specified times, each partner has the right to initiate a purchase or sale of its interest in the joint ventures. Under certain of the Company’s joint venture agreements, if certain return thresholds are achieved, the partners or the Company will be entitled to an additional promoted interest or payments.

The combined summarized balance sheets of the Company’s unconsolidated joint ventures are as follows:


	December 31, 2023		December 31, 2022
	(in thousands)
ASSETS
Real estate and development in process, net (1)	$	5,811,763	$	6,537,554
Other assets (2)	682,291		756,786
Total assets	$	6,494,054	$	7,294,340
LIABILITIES AND MEMBERS’/PARTNERS’ EQUITY
Mortgage and notes payable, net	$	3,351,873	$	4,022,746
Other liabilities (3)	361,357		716,271
Members’/Partners’ equity	2,780,824		2,555,323
Total liabilities and members’/partners’ equity	$	6,494,054	$	7,294,340
Company’s share of equity	$	1,278,483	$	1,238,929
Basis differentials (4)	58,933		391,556
Carrying value of the Company’s investments in unconsolidated joint ventures (5)	$	1,337,416	$	1,630,485

_______________

(1)At December 31, 2022, this amount included right of use assets - finance leases totaling approximately $248.9 million. At December 31, 2023 and December 31, 2022, this amount included right of use assets - operating leases totaling approximately $20.1 million and $21.2 million, respectively.

(2)At December 31, 2023, this amount included sales-type lease receivable, net totaling approximately $13.9 million.

(3)At December 31, 2022, this amount included lease liabilities - finance leases totaling approximately $382.2 million. At December 31, 2023 and December 31, 2022, this amount included lease liabilities - operating leases totaling approximately $30.5 million.

(4)This amount represents the aggregate difference between the Company’s historical cost basis and the basis reflected at the joint venture level, which is typically amortized over the life of the related assets and liabilities. Basis differentials

result from impairments of investments, acquisitions through joint ventures with no change in control and upon the transfer of assets that were previously owned by the Company into a joint venture. During the year ended December 31, 2023, the Company recognized an other-than-temporary impairment loss on its investments in Platform 16, 360 Park Avenue South, 200 Fifth Avenue and Safeco Plaza of approximately $155.2 million, $54.0 million, $33.4 million and $29.9 million, respectively, as well as a $35.8 million gain on investment related to Metropolitan Square, as described below in this Note 6. In addition, certain acquisition, transaction and other costs may not be reflected in the net assets at the joint venture level. The majority of the Company’s basis differences are as follows:


	December 31, 2023		December 31, 2022
Property	(in thousands)
Colorado Center	$	298,906	$	301,820
200 Fifth Avenue	58,308		94,497
Gateway Commons	48,971		47,808
Safeco Plaza	(29,678)		(15)
360 Park Avenue South	(116,534)		3,798
Dock 72	(95,521)		(98,980)
Platform 16	(143,052)		7,108

These basis differentials (excluding land) will be amortized over the remaining lives of the related assets and liabilities.

(5)Investments with deficit balances aggregating approximately $39.9 million and $85.4 million at December 31, 2023 and December 31, 2022, respectively, are reflected within Other Liabilities in the Company’s Consolidated Balance Sheets.

The combined summarized statements of operations of the Company’s unconsolidated joint ventures are as follows:


	Year ended December 31,
		2023		2022		2021
		(in thousands)
Total revenue (1)		$	612,589	$	512,078	$	383,649
Expenses
Operating		239,947		198,632		158,498
Transaction costs		301		837		470
Depreciation and amortization		197,228		181,041		147,121
Total expenses		437,476		380,510		306,089
Other income (expense)
Loss from early extinguishment of debt		(3)		(1,327)		—
Interest expense		(227,537)		(154,065)		(108,884)
Unrealized gain (loss) on derivative instruments		(6,582)		1,681		—
Gain on sales-type lease		2,737		—		—

Net loss		$	(56,272)	$	(22,143)	$	(31,324)

Company’s share of net loss		$	(19,599)	$	(2,551)	$	(10,254)
Gain on sale of investment (2)		—		—		10,257
Gain on investment (3)		35,756		—		—
Gain (loss) on sale / consolidation (3)(4)		28,412		—		—
Impairment losses on investments (5)		(272,603)		(50,705)		—
Basis differential (6)		(11,509)		(6,584)		(2,573)
Loss from unconsolidated joint ventures		$	(239,543)	$	(59,840)	$	(2,570)

_______________

(1)Includes straight-line rent adjustments of approximately $28.7 million, $62.9 million and $17.2 million for the years ended December 31, 2023, 2022 and 2021, respectively.

(2)During the year ended December 31, 2021, the Company completed the sale of its 50% ownership interest in Annapolis Junction NFM LLC. The Company recognized a gain on sale of investment of approximately $10.3 million.

(3)During the year ended December 31, 2023, the Company completed a restructuring of its ownership in Metropolitan Square, as described below in this Note 6.

(4)During the year ended December 31, 2023, the Company acquired its joint venture partner’s 45% ownership interest in Santa Monica Business Park, as described below in this Note 6.

(5)During the year ended December 31, 2023, the Company recognized an other-than-temporary impairment loss on its investments in Platform 16, 360 Park Avenue South, 200 Fifth Avenue and Safeco Plaza of approximately $155.2 million, $54.0 million, $33.4 million and $29.9 million, respectively, as described below in this Note 6. During the year ended December 31, 2022, the Company recognized an other-than-temporary impairment loss on its investment in the unconsolidated joint venture that owns Dock 72 in Brooklyn, New York totaling approximately $50.7 million.

(6)Includes straight-line rent adjustments of approximately $1.5 million, $0.5 million and $0.8 million for the years ended December 31, 2023, 2022 and 2020, respectively. Also includes net above-/below-market rent adjustments of approximately $0.8 million, $0.4 million and $0.4 million for the years ended December 31, 2023, 2022 and 2021, respectively.

On January 31, 2023, the Company acquired a 50% interest in a joint venture that owns 13100 and 13150 Worldgate Drive located in Herndon, Virginia for a gross purchase price of approximately $17.0 million. The acquisition was completed with available cash. 13100 and 13150 Worldgate Drive consists of two vacant office buildings aggregating approximately 350,000 rentable square feet and a 1,200-space structured parking deck situated on a 10-acre site. The joint venture intends to redevelop the property for residential use. There can be no assurance that the joint venture will commence the development as currently contemplated or at all.

On April 21, 2023, a joint venture in which the Company owns a 50% interest exercised an option to extend the maturity date of the construction loan collateralized by its 7750 Wisconsin Avenue property. Prior to the extension, the loan had a total commitment amount of approximately $252.6 million, bore interest at a variable rate equal to London Interbank Offered Rate (“LIBOR”) plus 1.25% per annum and was scheduled to mature on April 26, 2023, with two, one-year extension options, subject to certain conditions. The extended loan continued to bear interest at LIBOR plus 1.25% per annum through June 1, 2023 after which, the interest rate was converted to a variable rate equal to Term Secured Overnight Finance Rate (“SOFR”) plus 1.35% per annum. The extended loan now matures on April 26, 2024, with a one-year extension option, subject to certain conditions (See Note 17). 7750 Wisconsin Avenue is a premier workplace with approximately 736,000 net rentable square feet located in Bethesda, Maryland.

On June 5, 2023, a joint venture in which the Company owns a 30% interest repaid the existing construction loan collateralized by its 500 North Capitol Street, NW property and obtained new mortgage loans with related parties. At the time of the repayment, the outstanding balance of the loan totaled approximately $105.0 million and the loan was scheduled to mature on June 6, 2023. The new mortgage loans have an aggregate principal balance of $105.0 million, bear interest at a weighted average fixed rate of 6.83% per annum and mature on June 5, 2026. The Company’s portion of the mortgage loans, $10.5 million, has been reflected as a Related Party Note Receivable on the Company’s Consolidated Balance Sheets. 500 North Capitol Street, NW is an approximately 231,000 net rentable square foot premier workplace in Washington, DC.

On June 28, 2023, a joint venture in which the Company owns a 25% interest exercised an option to extend by 30 days the maturity date of the loan collateralized by its 3 Hudson Boulevard property. At the time of the extension, the loan had an outstanding balance of $80.0 million, bore interest at a variable rate equal to LIBOR plus 3.50% per annum and was scheduled to mature on July 13, 2023, with two extension options (30 days and 180 days, respectively), subject to certain conditions. Following the extension, the modified loan was scheduled to mature on August 13, 2023, with one 180-day extension option, subject to certain conditions. The extended loan continued to bear interest at a variable rate equal to LIBOR plus 3.50% per annum for the period from June 28, 2023 through July 6, 2023. For the period commencing on July 7, 2023 through the maturity date, the modified loan bears interest at a variable rate equal to Term SOFR plus approximately 3.61% per annum. On August 11, 2023, the joint venture exercised its second extension option of 180 days. The extended loan now matures on February 9, 2024 (See Note 17). As of December 31, 2023, the loan had approximately $28.0 million of accrued interest due at the maturity date. 3 Hudson Boulevard consists of land and improvements held for future development located in New York, New York.

On July 28, 2023, a joint venture in which the Company has a 50% interest modified and exercised an option to extend by one year the maturity date of its loan collateralized by 100 Causeway Street. At the time of the modification and extension, the loan had an outstanding balance totaling approximately $340.6 million, bore interest at Term SOFR plus 1.60% per annum, and was scheduled to mature on September 5, 2023. Following the modification and extension, the loan had an outstanding balance of $336.6 million, which included an approximately

$4.0 million principal repayment, bears interest at Term SOFR plus 1.48% per annum, and matures on September 5, 2024, with an additional one-year extension option, subject to certain conditions. 100 Causeway Street is an approximately 634,000 net rentable square foot premier workplace located in Boston, Massachusetts and is approximately 95% leased.

On September 1, 2023, a joint venture in which the Company has a 49% interest completed and fully placed in-service 751 Gateway, an approximately 231,000 net rentable square foot laboratory/life sciences project in South San Francisco, California. The property is 100% leased.

On September 6, 2023, a joint venture in which the Company has a 50% interest modified the loan collateralized by its Hub on Causeway - Podium property. At the time of the modification, the loan had an outstanding balance of approximately $174.3 million, bore interest at Term SOFR plus 2.35% per annum, and was scheduled to mature on September 6, 2023. Following the modification, the modified loan had an outstanding balance of $154.3 million, which included an approximately $20.0 million principal repayment, bore interest at Daily SOFR plus 2.50% per annum, and matures on September 8, 2025, with a one-year extension option, subject to certain conditions. On September 8, 2023, the joint venture entered into interest rate swap contracts with notional amounts aggregating approximately $154.3 million through September 2, 2025, resulting in a fixed interest rate of approximately 7.35% per annum through the expiration of the interest rate swap contracts. The Hub on Causeway - Podium is an approximately 383,000 net rentable square foot premier workplace located in Boston, Massachusetts and is approximately 94% leased.

On September 13, 2023, a joint venture in which the Company owned a 20% equity interest completed the first step of a two-step restructuring of its ownership in Metropolitan Square. The two-step restructuring resulted in (i) an affiliate of the existing mezzanine lender purchasing the property and becoming the new property owner and the Company no longer having an equity interest in the property and (ii) the Company becoming a co-lender of up to $20.0 million under a new $100.0 million mezzanine loan (“New Mezz Loan”). Prior to the restructuring, the property was encumbered by an aggregate of $420.0 million of debt, consisting of a senior loan with an outstanding principal balance of $305.0 million (“Senior Loan”) and the existing $115.0 million mezzanine loan (“Existing Mezz Loan”). The joint venture completed step one of the restructuring on September 13, 2023, resulted in, among other things, (i) the cessation of the Company’s obligation to fund future investments through its then 20% equity interest, which resulted in the recognition of gain on investment of approximately $35.8 million related to its deficit investment balance, which was primarily due to excess distributions, and (ii) the removal of the property from the Company’s in-service portfolio. On October 2, 2023, step two of the restructuring was completed and included (i) the sale of the property, which resulted in a loss on the sale of approximately $1.5 million and assignment of the Senior Loan to the new owner, and (ii) the closing of the New Mezz Loan (See Note 9). In addition, the Company will continue to provide property management and leasing services to the property with the potential to earn additional incentive fees. Metropolitan Square is a 657,000 net rentable square foot premier workplace located at 655 15th Street, NW in the heart of downtown Washington, DC.

On October 31, 2023, a joint venture in which the Company has a 50% interest modified the lease of a third-party hotel developer/operator at its Hub on Causeway – Hotel Air Rights property. The third-party hotel developer/operator paid $4.5 million in connection with this modification to fulfill its obligation to repay the joint venture’s investment. This modification resulted in a reassessment of the lease classification per ASC 842. Based on this reassessment this lease was reclassified as a sales-type lease. The joint venture recorded a sales-type lease receivable of approximately $18.6 million. In addition, the joint venture recorded a gain on sales-type lease of approximately $2.7 million associated with the derecognition of the asset.

On December 14, 2023, the Company completed the acquisition of its joint venture partner’s 45% ownership interest in the joint venture that owns Santa Monica Business Park for a purchase price of $38.0 million and the Company acquired net working capital, including cash and cash equivalents of approximately $20 million. Prior to the acquisition, the Company had a 55% ownership interest in the joint venture and accounted for it under the equity method of accounting. The acquisition resulted in the Company having full ownership of the joint venture such that the Company now accounts for the assets, liabilities, and operations of it on a consolidated basis in its financials statements instead of under the equity method of accounting (See Note 3) and as a result recognized a gain on consolidation of approximately $29.9 million.

On December 14, 2023, the Company completed the acquisition of its joint venture partner’s approximate 29% ownership interest in the joint venture that owns 360 Park Avenue South for a purchase price of $1, increasing the Company’s ownership in the joint venture to approximately 71%. The Company also assumed the partner’s share of the joint venture’s cash and working capital aggregating approximately $25.4 million, as well as the partner’s

share of the outstanding $220.0 million mortgage debt. 360 Park Avenue South, a 20-story, approximately 450,000 square foot premier workplace, is currently under re-development.

Impairments

The Company’s investments in unconsolidated joint ventures are reviewed for indicators of impairment on a quarterly basis and the Company records impairment charges when events or circumstances indicate that a decline in the fair values below the carrying amounts has occurred and such decline is other-than-temporary. During the year ended December 31, 2023, the Company continued to evaluate declining market conditions and underlying key assumptions of certain investments in unconsolidated joint ventures, including the receipt and consideration of certain third-party joint venture property appraisals. Such evaluation of key impairment indicators resulted in the Company determining that the decline in value, for certain joint venture properties, was other-than-temporary and therefore the Company recorded impairment charges during the year ended December 31, 2023, as described below.

During the year ended December 31, 2023, a joint venture in which the Company has a 55% interest elected to pause vertical construction on Platform 16 in San Jose, California. Platform 16 was planned to be constructed in phases to best accommodate market demand. The first phase of the development project included the construction of an approximately 390,000 net rentable square foot premier workplace building and below-grade parking garage. The joint venture intends to complete the construction of the below-grade parking garage and building foundation elements over the next several months to facilitate a restart of construction in the future as demand improves. Upon electing to pause vertical construction, the Company performed an analysis to determine if there was an other-than temporary impairment. Based on the market rent assumptions and new expected timeline for completion of the project, as of June 30, 2023, the Company concluded there was not an other-than temporary impairment present. During the three months ended September 30, 2023, the real estate and leasing conditions in the San Jose, California market continued to deteriorate and the Company further extended its construction pause assumption. These conditions, combined with a decrease in market rent assumptions, resulted in the Company recognizing a non-cash impairment charge totaling approximately $155.2 million, which represented the decline in the fair value below the carrying value of the Company’s investment in the unconsolidated joint venture that owns Platform 16. The Company determined that its investment was categorized within Level 3 of the fair value hierarchy, as it utilized significant unobservable inputs in its assessment, including an exit capitalization rate of 6.0%, and a discount rate of 12.0%.

During the year ended December 31, 2023, the Company recognized a non-cash impairment charge totaling approximately $54.0 million, which represented the decline in the fair value below the carrying value of the Company’s investment in the unconsolidated joint venture that owns 360 Park Avenue South. The Company assessed the impairment and concluded that it was other than temporary. The Company determined that its investment was categorized within Level 3 of the fair value hierarchy, as it utilized significant unobservable inputs in its assessment, including an exit capitalization rate of 5.5% and leasing the currently available space over a longer period of time ending in 2026. 360 Park Avenue South is currently under redevelopment to be a premier workplace with approximately 450,000 net rentable square feet located in New York City, New York.

During the year ended December 31, 2023, the Company recognized a non-cash impairment charge totaling approximately $33.4 million, which represented the decline in the fair value below the carrying value of the Company’s investment in the unconsolidated joint venture that owns 200 Fifth Avenue. The Company assessed the impairment and concluded that it was other than temporary. The Company determined that its investment was categorized within Level 3 of the fair value hierarchy, as it utilized significant unobservable inputs in its assessment, including an exit capitalization rate of 5.0% and a discount rate of 8.0%. 200 Fifth Avenue is a premier workplace with approximately 855,000 net rentable square feet located in New York City, New York.

During the year ended December 31, 2023, the Company recognized a non-cash impairment charge totaling approximately $29.9 million, which represented the decline in the fair value below the carrying value of the Company’s investment in the unconsolidated joint venture that owns Safeco Plaza. The Company assessed the impairment and concluded that it was other than temporary. The Company determined that its investment was categorized within Level 3 of the fair value hierarchy, as it utilized significant unobservable inputs in its assessment, including an exit capitalization rate of 5.5%, a discount rate of 8.0% and a major lobby and repositioning renovation. Safeco Plaza is a premier workplace with approximately 780,000 net rentable square feet located in Seattle, Washington.

Related Party Transactions (Details) $ in Thousands		12 Months Ended
Related Party Transactions (Details) $ in Thousands	Dec. 31, 2023 USD ($) ft² shares	Dec. 31, 2023 USD ($) ft² nonemployeedirectors shares	Dec. 31, 2022 USD ($) shares	Dec. 31, 2021 USD ($)	Jun. 05, 2023 USD ($) ft²	Jun. 04, 2023 USD ($)	Dec. 16, 2021 shares
Related Party Transaction [Line Items]
Interest and Other Income		$ 69,964	$ 11,940	$ 5,704
Number Of Non Employee Directors Electing To Receive Deferred Stock Units \| nonemployeedirectors		8
Separate Unrestricted Cash For Deferred Compensation Plan.	$ 36,100	$ 36,100	32,300
Liability for directors	$ 458,329	$ 458,329	$ 417,545
Common stock, shares issued \| shares	157,019,766	157,019,766	156,836,767
Reedemable deferred stock units, units \| shares	119,471	119,471	97,853
500 North Capitol Street, NW \| Unconsolidated Properties
Related Party Transaction [Line Items]
Net Rentable Area (in sf) \| ft²					231,000
Ownership Percentage					30.00%
Debt					$ 105,000	$ 105,000
Debt, Weighted Average Interest Rate					6.83%
Related Party
Related Party Transaction [Line Items]
Related party note receivable, net	$ 88,779	$ 88,779	$ 78,576
Related Party \| 500 North Capitol Street, NW \| Unconsolidated Properties
Related Party Transaction [Line Items]
Debt					$ 105,000
Debt, Weighted Average Interest Rate					6.83%
Related Party \| 500 North Capitol Street, NW \| Unconsolidated Properties \| Notes Receivables [Member]
Related Party Transaction [Line Items]
Interest and Other Income		600
Related party note receivable, net					$ 10,500
Debt Instrument, Interest Rate, Stated Percentage					8.03%
Boston Properties Limited Partnership
Related Party Transaction [Line Items]
Interest and Other Income		69,964	11,940	5,704
Liability for directors	$ 458,329	$ 458,329	$ 417,545
Reedemable deferred stock units, units \| shares	119,471	119,471	97,853
Boston Properties Limited Partnership \| Related Party
Related Party Transaction [Line Items]
Related party note receivable, net	$ 88,779	$ 88,779	$ 78,576
3 Hudson Boulevard [Member]
Related Party Transaction [Line Items]
Net Rentable Area (in sf) \| ft²	2,000,000	2,000,000
Ownership Percentage	25.00%	25.00%
3 Hudson Boulevard [Member] \| Related Party
Related Party Transaction [Line Items]
Interest and Other Income		$ 8,900	5,600	3,600
Director Cessation Member [Member] \| Related Party
Related Party Transaction [Line Items]
Common stock, shares issued \| shares							498
Related Party \| 3 Hudson Boulevard [Member] \| Unconsolidated Properties \| Notes Receivables [Member]
Related Party Transaction [Line Items]
Related party note receivable, net	$ 80,000	80,000
Related Party \| 3 Hudson Boulevard [Member] \| Unconsolidated Properties \| Notes Receivables [Member] \| Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate
Related Party Transaction [Line Items]
Debt Instrument, Basis Spread on Variable Rate	3.61%
Director \| Related Party
Related Party Transaction [Line Items]
Separate Unrestricted Cash For Deferred Compensation Plan.	$ 800	800	600
Liability for directors	$ 800	800	600
Real Estate Brokerage Firm \| Related Party
Related Party Transaction [Line Items]
Operating Costs and Expenses		$ 500	$ 1,600	$ 1,900

Insider Trading Arrangements	3 Months Ended
Insider Trading Arrangements	Dec. 31, 2023
Trading Arrangements, by Individual
Rule 10b5-1 Arrangement Adopted	false
Non-Rule 10b5-1 Arrangement Adopted	false
Rule 10b5-1 Arrangement Terminated	false
Non-Rule 10b5-1 Arrangement Terminated	false

Unsecured Term Loan (Details) $ in Thousands					12 Months Ended
Unsecured Term Loan (Details) $ in Thousands	Dec. 31, 2023 USD ($)	Jan. 04, 2023 USD ($) mo Rate	Dec. 31, 2022 USD ($)	May 17, 2022 USD ($)	Dec. 31, 2023 USD ($)	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)
Debt Instrument [Line Items]
Repayments of Unsecured Debt					$ 500,000	$ 0	$ 1,841,500
Payment for Debt Extinguishment or Debt Prepayment Cost					0	0	$ 43,036
Unsecured term loan, net	$ 1,198,301		$ 730,000		1,198,301	730,000
2022 Unsecured Term Loan
Debt Instrument [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity				$ 730,000
Debt Instrument, Maturity Date				May 16, 2023
Repayments of Unsecured Debt		$ 730,000
Payment for Debt Extinguishment or Debt Prepayment Cost		0
Unsecured term loan, net			$ 730,000	$ 730,000		$ 730,000
2022 Unsecured Term Loan \| Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate			0.95%
2023 Unsecured Term Loan
Debt Instrument [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity		1,200,000
Line of Credit, Additional Borrowing Capacity		$ 300,000
Debt Instrument, Maturity Date		May 16, 2024
Number of extensions		1
Extension Option (in months) \| mo		12
Proceeds from Unsecured Lines of Credit		$ 1,200,000
Debt Instrument, Basis Spread on Variable Rate \| Rate		1.00%
Debt Instrument, Interest Rate Terms		At BPLP’s option, loans under the 2023 Unsecured Term Loan will bear interest at a rate per annum equal to (1) a base rate equal to the greatest of (a) the Federal Funds rate plus 0.5%, (b) the administrative agent’s prime rate, (c) Term SOFR for a one-month period plus 1.00%, and (d) 1.00%, in each case, plus a margin ranging from 0 to 60 basis points based on BPLP’s credit rating; or (2) a rate equal to adjusted Term SOFR with a one-month period plus a margin ranging from 75 to 160 basis points based on BPLP’s credit rating. Based on BPLP’s credit rating upon entry into the credit agreement, the base rate margin is 0 basis points and the Term SOFR margin is 0.85%.
Unsecured term loan, net	$ 1,200,000				$ 1,200,000
2023 Unsecured Term Loan \| Minimum [Member]
Debt Instrument [Line Items]
Number of Additional Term Loans		1
2023 Unsecured Term Loan \| Fed Funds Effective Rate Overnight Index Swap Rate
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate \| Rate		0.50%
2023 Unsecured Term Loan \| Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate \| Rate		1.00%
2023 Unsecured Term Loan \| Base Rate [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate		0.00%
2023 Unsecured Term Loan \| Base Rate [Member] \| Maximum [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate \| Rate		0.60%
2023 Unsecured Term Loan \| Base Rate [Member] \| Minimum [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate \| Rate		0.00%
2023 Unsecured Term Loan \| Adjusted Term Secured Overnight Financing Rate (Adjusted Term SOFR)
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	0.85%	0.85%
2023 Unsecured Term Loan \| Adjusted Term Secured Overnight Financing Rate (Adjusted Term SOFR) \| Maximum [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate \| Rate		1.60%
2023 Unsecured Term Loan \| Adjusted Term Secured Overnight Financing Rate (Adjusted Term SOFR) \| Minimum [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate \| Rate		0.75%

Investments in Unconsolidated Joint Ventures (Tables)

12 Months Ended

Dec. 31, 2023

Schedule of Equity Method Investments [Line Items]

Investments In Unconsolidated Joint Ventures

The investments in unconsolidated joint ventures consist of the following at December 31, 2023 and December 31, 2022:


					Carrying Value of Investment (1)
Entity	Properties	Nominal % Ownership			December 31, 2023		December 31, 2022
					(in thousands)
Square 407 Limited Partnership	Market Square North	50.00	%		$	(5,996)	$	(6,198)
BP/CRF Metropolitan Square LLC	Metropolitan Square	20.00	%	(2)	—		(37,629)
901 New York, LLC	901 New York Avenue	25.00	%	(3)	(11,764)		(12,493)
WP Project Developer LLC	Wisconsin Place Land and Infrastructure	33.33	%	(4)	30,375		31,971
500 North Capitol Venture LLC	500 North Capitol Street, NW	30.00	%		(10,253)		(9,185)
501 K Street LLC	1001 6th Street	50.00	%		44,774		42,922
Podium Developer LLC	The Hub on Causeway - Podium	50.00	%		45,201		46,839
Residential Tower Developer LLC	Hub50House	50.00	%		40,235		45,414
Hotel Tower Developer LLC	The Hub on Causeway - Hotel Air Rights	50.00	%		13,494		12,366
Office Tower Developer LLC	100 Causeway Street	50.00	%		57,660		59,716
1265 Main Office JV LLC	1265 Main Street	50.00	%		3,585		3,465
BNY Tower Holdings LLC	Dock 72	50.00	%	(5)	(11,890)		(19,921)

CA-Colorado Center, LLC	Colorado Center	50.00	%		237,815		233,862
7750 Wisconsin Avenue LLC	7750 Wisconsin Avenue	50.00	%		50,064		52,152
BP-M 3HB Venture LLC	3 Hudson Boulevard	25.00	%		115,103		116,397
SMBP Venture LP	Santa Monica Business Park	55.00	%	(6)	—		164,735
Platform 16 Holdings LP	Platform 16	55.00	%	(7)(8)	45,564		158,109
Gateway Portfolio Holdings LLC	Gateway Commons	50.00	%		376,834		324,038
Rosecrans-Sepulveda Partners 4, LLC	Beach Cities Media Campus	50.00	%		27,034		27,000
Safeco Plaza REIT LLC	Safeco Plaza	33.67	%	(8)(9)	44,734		69,785
360 PAS Holdco LLC	360 Park Avenue South	71.11	%	(8)(10)	42,988		114,992
PR II/BXP Reston Gateway LLC	Skymark - Reston Next Residential	20.00	%		15,184		11,351
751 Gateway Holdings LLC	751 Gateway	49.00	%		93,411		80,714
200 Fifth Avenue JV LLC	200 Fifth Avenue	26.69	%	(8)	75,718		120,083
ABXP Worldgate Investments LLC	13100 and 13150 Worldgate Drive	50.00	%		17,546		N/A
					$	1,337,416	$	1,630,485

_______________

(2)During the year ended December 31, 2023, the Company completed a restructuring of its ownership in Metropolitan Square, as described below in this Note 6.

(5)This property includes net equity balances from the amenity joint venture.

(7)At December 31, 2022, this entity was a VIE.

(8)During the year ended December 31, 2023, the Company recognized an other-than-temporary impairment loss on its investment.

Schedule Of Balance Sheets Of The Unconsolidated Joint Ventures [Text Block]

The combined summarized balance sheets of the Company’s unconsolidated joint ventures are as follows:


	December 31, 2023		December 31, 2022
	(in thousands)
ASSETS
Real estate and development in process, net (1)	$	5,811,763	$	6,537,554
Other assets (2)	682,291		756,786
Total assets	$	6,494,054	$	7,294,340
LIABILITIES AND MEMBERS’/PARTNERS’ EQUITY
Mortgage and notes payable, net	$	3,351,873	$	4,022,746
Other liabilities (3)	361,357		716,271
Members’/Partners’ equity	2,780,824		2,555,323
Total liabilities and members’/partners’ equity	$	6,494,054	$	7,294,340
Company’s share of equity	$	1,278,483	$	1,238,929
Basis differentials (4)	58,933		391,556
Carrying value of the Company’s investments in unconsolidated joint ventures (5)	$	1,337,416	$	1,630,485

_______________

(2)At December 31, 2023, this amount included sales-type lease receivable, net totaling approximately $13.9 million.


	December 31, 2023		December 31, 2022
Property	(in thousands)
Colorado Center	$	298,906	$	301,820
200 Fifth Avenue	58,308		94,497
Gateway Commons	48,971		47,808
Safeco Plaza	(29,678)		(15)
360 Park Avenue South	(116,534)		3,798
Dock 72	(95,521)		(98,980)
Platform 16	(143,052)		7,108

These basis differentials (excluding land) will be amortized over the remaining lives of the related assets and liabilities.

Statements Of Operations Of The Joint Ventures

The combined summarized statements of operations of the Company’s unconsolidated joint ventures are as follows:


	Year ended December 31,
		2023		2022		2021
		(in thousands)
Total revenue (1)		$	612,589	$	512,078	$	383,649
Expenses
Operating		239,947		198,632		158,498
Transaction costs		301		837		470
Depreciation and amortization		197,228		181,041		147,121
Total expenses		437,476		380,510		306,089
Other income (expense)
Loss from early extinguishment of debt		(3)		(1,327)		—
Interest expense		(227,537)		(154,065)		(108,884)
Unrealized gain (loss) on derivative instruments		(6,582)		1,681		—
Gain on sales-type lease		2,737		—		—

Net loss		$	(56,272)	$	(22,143)	$	(31,324)

Company’s share of net loss		$	(19,599)	$	(2,551)	$	(10,254)
Gain on sale of investment (2)		—		—		10,257
Gain on investment (3)		35,756		—		—
Gain (loss) on sale / consolidation (3)(4)		28,412		—		—
Impairment losses on investments (5)		(272,603)		(50,705)		—
Basis differential (6)		(11,509)		(6,584)		(2,573)
Loss from unconsolidated joint ventures		$	(239,543)	$	(59,840)	$	(2,570)

_______________

(1)Includes straight-line rent adjustments of approximately $28.7 million, $62.9 million and $17.2 million for the years ended December 31, 2023, 2022 and 2021, respectively.

(3)During the year ended December 31, 2023, the Company completed a restructuring of its ownership in Metropolitan Square, as described below in this Note 6.

(4)During the year ended December 31, 2023, the Company acquired its joint venture partner’s 45% ownership interest in Santa Monica Business Park, as described below in this Note 6.

Derivative Instruments and Hedging Activities Gain (Loss) (Details) - USD ($)
$ in Thousands

12 Months Ended

Dec. 31, 2023

Dec. 31, 2022

Dec. 31, 2021

Derivative Instruments, Gain (Loss) [Line Items]

Amount of gain (loss) related to the effective portion recognized in other comprehensive income

^[1]

$ (14,405)

$ 19,396

$ 8,544

Amount of gain (loss) related to the effective portion subsequently reclassified to earnings

^[2]

6,703

6,707

6,704

Amount of gain (loss) relate do the ineffective portion and amount excluded from effectiveness testing

$ 0

[1]	Includes the Company’s share of gain (loss) related to the effective portion of derivatives outstanding at its unconsolidated joint venture properties.
[2]	Consists of amounts from previous interest rate programs.

Commitments And Contingencies	12 Months Ended
Commitments And Contingencies	Dec. 31, 2023
Commitments and Contingencies Disclosure [Abstract]
Commitments And Contingencies	9. Commitments and Contingencies General In the normal course of business, the Company guarantees its performance of services or indemnifies third parties against its negligence. In addition, in the normal course of business, the Company guarantees to certain tenants the obligations of its subsidiaries for the payment of tenant improvement allowances and brokerage commissions in connection with their leases and limited costs arising from delays in delivery of their premises. The Company had letter of credit and performance obligations related to lender and development requirements that total approximately $21.6 million at December 31, 2023. Certain of the Company’s joint venture agreements include provisions whereby, at certain specified times, each partner has the right to initiate a purchase or sale of its interest in the joint ventures. From time to time, under certain of the Company’s joint venture agreements, if certain return thresholds are achieved, either the Company or its partners may be entitled to an additional promoted interest or payments. From time to time, the Company (or ventures in which the Company has an ownership interest) has agreed, and may in the future agree, to (1) guarantee portions of the principal, interest and other amounts in connection with their borrowings, (2) provide customary environmental indemnifications and nonrecourse carve-outs (e.g., guarantees against fraud, misrepresentation and bankruptcy) in connection with their borrowings and (3) provide guarantees to lenders, tenants and other third parties for the completion of development projects. The Company has agreements with its outside or joint venture partners whereby the partners agree to reimburse the joint venture for their share of any payments made under the guarantee. In some cases, the Company earns a fee from the applicable joint venture for providing the guarantee. In connection with the refinancing of 767 Fifth Avenue’s (the General Motors Building) secured loan by the Company’s consolidated joint venture entity, 767 Venture, LLC, the Company guaranteed the consolidated entity’s obligation to fund various reserves for tenant improvement costs and allowances, leasing commissions and free rent obligations in lieu of cash deposits. As of December 31, 2023, the maximum funding obligation under the guarantee was approximately $8.5 million. The Company earns a fee from the joint venture for providing the guarantee and has an agreement with the outside partners to reimburse the joint venture for their share of any payments made under the guarantee. As of December 31, 2023, no amounts related to the guarantee were recorded as liabilities in the Company’s consolidated financial statements. In connection with the development of the Company’s 290 Binney Street project located in Cambridge, Massachusetts, which commenced on January 5, 2023 (see Note 3), the Cambridge Zoning Ordinance requires that a building permit for the construction of a residential project of at least 400,000 square feet be issued prior to or concurrently with the issuance of a building permit for the commercial building. 290 Binney Street and the residential project are components of the Company’s future life sciences development project located in the heart of Kendall Square in Cambridge, Massachusetts. When completed the Company expects the project will consist of two premier workplace properties aggregating approximately 1.1 million rentable square feet of life sciences space and the approximately 400,000 square foot residential building. The commencement of construction of each phase of the overall project is subject to various conditions, some of which are not within the Company’s control. There can be no assurance that the conditions will be satisfied or that the Company will commence the development of the remaining phases on the terms and schedule currently contemplated or at all. On October 2, 2023, the restructuring of Metropolitan Square was completed (See Note 6), which included, among other items, the closing of the New Mezz Loan with a maximum principal amount of $100.0 million, which loan is subordinate only to the Senior Loan. The New Mezz Loan may be drawn upon for future lease-up, operating and other costs on an as needed basis, and amounts borrowed will bear interest at a per annum rate of 12%, compounded monthly. The Company will fund 20%, or up to $20.0 million, of any amounts borrowed under the New Mezz Loan. As of December 31, 2023, the Company has funded approximately $1.7 million. Legal Matters The Company is subject to various legal proceedings and claims that arise in the ordinary course of business. These matters are generally covered by insurance. Management believes that the final outcome of such matters will not have a material adverse effect on the financial position, results of operations or liquidity of the Company. In connection with the acquisition of a premier workplace in New York City in 2010, the Company entered into an agreement with the seller pursuant to which the seller could earn various fees based on the future leasing performance of the property. The Company initially accrued approximately $1.5 million as an estimate of the fees it would owe the seller. The seller filed suit against the Company claiming that consideration significantly in excess of the initial reserve amount is owed under the agreement in 2020. The disagreement between the Company and the seller involves material issues of contract interpretation and, more importantly, the method of calculating fees, including various inputs (both facts and assumptions) that drive the calculation. In February 2024, a summary judgment was issued interpreting certain sections of the agreement in favor of the seller’s claims. The Company believes it has meritorious defenses to the seller’s claims, is disputing the seller’s calculations and intends to continue defending itself vigorously. However, there can be no assurance that the Company will prevail in the lawsuit. If the court ultimately agrees with the seller’s calculations, then amounts due to the seller could theoretically be as high as the additional $31 million claimed in the seller’s complaint, plus interest. Although the Company rejects those calculations, there can be no assurance that the Company’s ultimate liability will not be significantly greater than its established accrual. Concentrations of Credit Risk Management of the Company performs ongoing credit evaluations of tenants and may require tenants to provide some form of credit support such as corporate guarantees, security deposits and/or other financial guarantees. Although the Company’s properties are geographically diverse and tenants operate in a variety of industries, to the extent the Company has a significant concentration of rental revenue from any single tenant, the inability of that tenant to make its lease payments could have an adverse effect on the Company. Insurance The Company’s property insurance program per occurrence limits are $1.0 billion for its portfolio insurance program, including coverage for acts of terrorism other than nuclear, biological, chemical or radiological terrorism (“Terrorism Coverage”). The Company also carries $1.35 billion of property insurance in excess of the $1.0 billion of coverage in the Company’s property insurance program for 601 Lexington Avenue, New York, New York, consisting of $750 million of property and Terrorism Coverage in excess of the Company’s property insurance program and $600 million of Terrorism Coverage only in excess of the $1.75 billion of coverage. Certain properties, including the General Motors Building located at 767 Fifth Avenue in New York, New York (“767 Fifth Avenue”), are currently insured in separate insurance programs. The property insurance program per occurrence limits for 767 Fifth Avenue are $1.625 billion, including Terrorism Coverage. The Company also currently carries nuclear, biological, chemical and radiological terrorism insurance coverage for acts of terrorism certified under the Federal Terrorism Risk Insurance Act (as amended, “TRIA”) (“NBCR Coverage”), which is provided by IXP as a direct insurer, for the properties in the Company’s portfolio, including 767 Fifth Avenue, but excluding certain other properties owned in joint ventures with third parties or which the Company manages. The per occurrence limit for NBCR Coverage is $1.0 billion. Under TRIA, after the payment of the required deductible and coinsurance, the NBCR Coverage provided by IXP is backstopped by the Federal Government if the aggregate industry insured losses resulting from a certified act of terrorism exceed a “program trigger.” The program trigger is $200 million, the coinsurance is 20% and the deductible is 20% of the premiums earned by the insurer for the year prior to a claim. If the Federal Government pays out for a loss under TRIA, it is mandatory that the Federal Government recoup the full amount of the loss from insurers offering TRIA coverage after the payment of the loss pursuant to a formula in TRIA. The Company may elect to terminate the NBCR Coverage if the Federal Government seeks recoupment for losses paid under TRIA, if TRIA is not extended after its expiration on December 31, 2027, if there is a change in its portfolio or for any other reason. The Company intends to continue to monitor the scope, nature and cost of available terrorism insurance. The Company also currently carries earthquake insurance on its properties located in areas known to be subject to earthquakes. Specifically, the Company currently carries earthquake insurance which covers its San Francisco and Los Angeles regions with a $330 million per occurrence limit, and a $330 million annual aggregate limit, $30 million of which is provided by IXP, as a direct insurer. This insurance is subject to a deductible in the amount of 5% of the value of the affected property. In addition, the Company currently carries earthquake insurance which covers its Seattle region with a $110 million per occurrence limit, and a $110 million annual aggregate limit. This insurance is subject to a deductible in the amount of 2% of the value of the affected property. The amount of the Company’s earthquake insurance coverage may not be sufficient to cover losses from earthquakes. In addition, the amount of earthquake coverage could impact the Company’s ability to finance properties subject to earthquake risk. The Company may discontinue earthquake insurance or change the structure of its earthquake insurance program on some or all of its properties in the future if the premiums exceed the Company’s estimation of the value of the coverage. IXP, a captive insurance company which is a wholly-owned subsidiary of the Company, acts as a direct insurer with respect to a portion of the Company’s earthquake insurance coverage for its Greater San Francisco and Los Angeles properties and the Company’s NBCR Coverage. Insofar as the Company owns IXP, it is responsible for its liquidity and capital resources, and the accounts of IXP are part of the Company’s consolidated financial statements. In particular, if a loss occurs which is covered by the Company’s NBCR Coverage but is less than the applicable program trigger under TRIA, IXP would be responsible for the full amount of the loss without any backstop by the Federal Government. IXP would also be responsible for any recoupment charges by the Federal Government in the event losses are paid out and its insurance policy is maintained after the payout by the Federal Government. If the Company experiences a loss and IXP is required to pay under its insurance policy, the Company would ultimately record the loss to the extent of the required payment. Therefore, insurance coverage provided by IXP should not be considered as the equivalent of third-party insurance, but rather as a modified form of self-insurance. In addition, BPLP has issued a guarantee to cover liabilities of IXP in the amount of $20.0 million. The Company continues to monitor the state of the insurance market in general, and the scope and costs of coverage for acts of terrorism, earthquakes, pandemics and cybersecurity incidents, in particular, but the Company cannot anticipate what coverage will be available on commercially reasonable terms in future policy years. There are other types of losses, such as from wars, for which the Company cannot obtain insurance at all or at a reasonable cost. With respect to such losses and losses from acts of terrorism, earthquakes, pandemics or other catastrophic events, if the Company experiences a loss that is uninsured or that exceeds policy limits, the Company could lose the capital invested in the damaged properties, as well as the anticipated future revenues from those properties. Depending on the specific circumstances of each affected property, it is possible that the Company could be liable for mortgage indebtedness or other obligations related to the property. Any such loss could materially and adversely affect the Company’s business and financial condition and results of operations. State and Local Tax Matters Because BXP is organized and qualifies as a REIT, it is generally not subject to federal income taxes, but is subject to certain state and local taxes. In the normal course of business, certain entities through which the Company owns real estate either have undergone, or are currently undergoing, tax audits. Although the Company believes that it has substantial arguments in favor of its positions in the ongoing audits, in some instances there is no controlling precedent or interpretive guidance on the specific point at issue. Collectively, tax deficiency notices received to date from the jurisdictions conducting the ongoing audits have not been material. However, there can be no assurance that future audits will not occur with increased frequency or that the ultimate result of such audits will not have a material adverse effect on the Company’s results of operations. Environmental Matters It is the Company’s policy to retain independent environmental consultants to conduct or update Phase I environmental assessments (which generally do not involve invasive techniques such as soil or ground water sampling) and asbestos surveys in connection with the Company’s acquisition of properties. These pre-purchase environmental assessments have not revealed environmental conditions that the Company believes will have a material adverse effect on its business, assets, financial condition, results of operations or liquidity, and the Company is not otherwise aware of environmental conditions with respect to its properties that the Company believes would have such a material adverse effect. However, from time to time environmental conditions at the Company’s properties have required and may in the future require environmental testing and/or regulatory filings, as well as remedial action. In February 1999, the Company (through a joint venture) acquired from Exxon Corporation a property in Massachusetts that was formerly used as a petroleum bulk storage and distribution facility and was known by the state regulatory authority to contain soil and groundwater contamination. The Company developed an office park on the property. The Company engaged a specially licensed environmental consultant to oversee the management of contaminated soil and groundwater that was disturbed in the course of construction. Under the property acquisition agreement, Exxon agreed to (1) bear the liability arising from releases or discharges of oil and hazardous substances which occurred at the site prior to the Company’s ownership, (2) continue monitoring and/or remediating such releases and discharges as necessary and appropriate to comply with applicable requirements, and (3) indemnify the Company for certain losses arising from preexisting site conditions. Any indemnity claim may be subject to various defenses and contractual limitations, including time limits, and there can be no assurance that the amounts paid under the indemnity, if any, would be sufficient to cover the liabilities arising from any such releases and discharges. Environmental investigations at some of the Company’s properties and certain properties owned by affiliates of the Company have identified groundwater contamination migrating from off-site source properties. In each case the Company engaged a licensed environmental consultant to perform the necessary investigations and assessments and to prepare any required submittals to the regulatory authorities. In each case the environmental consultant concluded that the properties qualify under the regulatory program or the regulatory practice for a status which eliminates certain deadlines for conducting response actions at a site. The Company also believes that these properties qualify for liability relief under certain statutory provisions or regulatory practices regarding upgradient releases. Although the Company believes that the current or former owners of the upgradient source properties may bear responsibility for some or all of the costs of addressing the identified groundwater contamination, the Company will take such further response actions (if any) that it deems necessary or advisable. Other than periodic testing at some of these properties, no such additional response actions are anticipated at this time. Some of the Company’s properties and certain properties owned by the Company’s affiliates are located in urban, industrial and other previously developed areas where fill or current or historical uses of the areas have caused site contamination. Accordingly, it is sometimes necessary to institute special soil and/or groundwater handling procedures and/or include particular building design features in connection with development, construction and other property operations in order to achieve regulatory closure and/or ensure that contaminated materials are addressed in an appropriate manner. In these situations, it is the Company’s practice to investigate the nature and extent of detected contamination, including potential issues associated with vapor intrusion concerns and/or potential contaminant migration to or from the subject property in ground water, assess potential liability risks and estimate the costs of required response actions and special handling procedures. The Company then uses this information as part of its decision-making process with respect to the acquisition, deal structure and/or development of the property. For example, the Company owns a parcel in Massachusetts which was formerly used as a quarry/asphalt batching facility. Pre-purchase testing indicated that the site contained relatively low levels of certain contaminants. The Company has developed an office park on this property. Prior to and during redevelopment activities, the Company engaged a specially licensed environmental consultant to monitor environmental conditions at the site and prepare necessary regulatory submittals based on the results of an environmental risk characterization. A submittal has been made to the regulatory authorities in order to achieve regulatory closure at this site. The submittal included an environmental deed restriction that mandates compliance with certain protective measures in a portion of the site where low levels of residual soil contamination have been left in place in accordance with applicable laws. The Company expects that resolution of the environmental matters relating to the above will not have a material impact on its business, assets, financial condition, results of operations or liquidity. However, the Company cannot assure you that it has identified all environmental liabilities at its properties, that all necessary remediation actions have been or will be undertaken at the Company’s properties or that the Company will be indemnified, in full or at all or that the Company will have insurance coverage, in the event that such environmental liabilities arise.

SEC Schedule, Article 12-28, Real Estate and Accumulated Depreciation

12 Months Ended

Dec. 31, 2023

SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation Disclosure [Abstract]

SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation Disclosure [Text Block]

Item 15. Exhibits and Financial Statement Schedules.

(a) Financial Statement Schedule


Boston Properties, Inc. Schedule 3—Real Estate and Accumulated Depreciation December 31, 2023 (dollars in thousands)
Property Name	Type	Location	Encumbrances			Original				Costs Capitalized Subsequent to Acquisition		Land and Improvements		Building and Improvements		Land Held for Development		Development and Construction in Progress		Total		Accumulated Depreciation		Year(s) Built/Renovated	Year(s) Acquired	Depreciable Lives (Years)

						Land		Building
767 Fifth Avenue (the General Motors Building)	Office	New York, NY	$	2,288,004		$	1,796,252	$	1,532,654	$	365,829	$	1,796,252	$	1,898,483	$	—	$	—	$	3,694,735	$	507,660	1968/2019	2013	(1)
Prudential Center	Office	Boston, MA	—			92,077		948,357		791,280		115,634		1,687,021		—		29,059		1,831,714		774,225		1965/1993/2002/2016-2017	1998/1999/2000	(1)
Embarcadero Center	Office	San Francisco, CA	—			179,697		847,410		524,483		195,986		1,355,604		—		—		1,551,590		781,405		1970/1989	1998-1999	(1)
399 Park Avenue	Office	New York, NY	—			339,200		700,358		408,846		354,107		1,094,297		—		—		1,448,404		482,752		1961/2018	2002	(1)
601 Lexington Avenue	Office	New York, NY	989,181			241,600		494,782		545,612		289,639		992,355		—		—		1,281,994		372,795		1977/1997/2021	2001	(1)
Salesforce Tower	Office	San Francisco, CA	—			200,349		946,205		7,623		200,349		953,828		—		—		1,154,177		159,274		2018	2013	(1)
200 Clarendon Street and Garage	Office	Boston, MA	—			219,543		667,884		251,372		250,910		887,889		—		—		1,138,799		338,529		1976	2010	(1)
250 West 55th Street	Office	New York, NY	—			285,263		603,167		52,917		285,263		656,084		—		—		941,347		198,081		2014	2007	(1)
100 Federal Street	Office	Boston, MA	—			131,067		435,954		127,199		131,067		563,153		—		—		694,220		172,079		1971-1975/2017	2012	(1)
Times Square Tower	Office	New York, NY	—			165,413		380,438		140,281		169,193		516,939		—		—		686,132		256,942		2004	2000	(1)
Madison Centre	Office	Seattle, WA	—			104,641		564,336		4,082		104,641		568,418		—		—		673,059		35,516		2017	2022	(1)
Carnegie Center	Office	Princeton, NJ	—			142,666		316,856		177,545		94,243		484,024		58,800		—		637,067		267,232		1983-2016	1998/1999/2000/2007/2014/2017/2019	(1)
Santa Monica Business Park	Office	Los Angeles, CA	295,649			46,360		410,421		164,229		210,471		410,535		4		—		621,010		865		1976-1980	2023	(1)
125 Broadway	Office	Cambridge, MA	—			126,364		433,662		4,000		126,364		437,662		—		—		564,026		20,717		2000	2022	(1)
Reston Next	Office	Reston, VA	—			35,549		525,277		—		2,901		557,925		—		—		560,826		32,504		2022	1998	(1)
Atlantic Wharf	Office	Boston, MA	—			63,988		454,537		39,399		63,988		493,936		—		—		557,924		180,686		2011	2007	(1)
2100 Pennsylvania Avenue	Office	Washington, DC	—			185,203		324,206		—		185,203		324,206		—		—		509,409		20,768		2023	N/A	(1)
599 Lexington Avenue	Office	New York, NY	—			81,040		100,507		258,659		87,852		352,354		—		—		440,206		197,429		1986	1997	(1)
Fountain Square	Office	Reston, VA	—			56,853		306,298		49,874		56,853		356,172		—		—		413,025		111,481		1986-1990	2012	(1)
510 Madison Avenue	Office	New York, NY	—			103,000		253,665		33,100		103,000		286,765		—		—		389,765		104,052		2012	2010	(1)
325 Main Street	Office	Cambridge, MA	—		(2)	21,596		312,492		30,933		21,596		343,425		—		—		365,021		14,833		2022	1997	(1)
680 Folsom Street	Office	San Francisco, CA	—			72,545		219,766		8,026		72,545		227,792		—		—		300,337		80,964		2014	2012	(1)
145 Broadway	Office	Cambridge, MA	—			121		273,013		26,359		23,367		276,126		—		—		299,493		35,390		2019	1997	(1)
2200 Pennsylvania Avenue	Office	Washington, DC	—			—		183,541		114,090		102,979		194,652		—		—		297,631		77,357		2011	2008	(1)
South of Market and Democracy Tower	Office	Reston, VA	—			13,603		237,479		30,952		13,687		268,347		—		—		282,034		108,973		2008-2009	2003	(1)
Bay Colony Corporate Center	Office	Waltham, MA	—			18,789		148,451		96,639		18,789		240,416		4,674		—		263,879		113,123		1985-1989	2011	(1)
535 Mission Street	Office	San Francisco, CA	—			40,933		148,378		4,629		40,934		153,006		—		—		193,940		46,615		2015	2013	(1)


Boston Properties, Inc. Schedule 3—Real Estate and Accumulated Depreciation December 31, 2023 (dollars in thousands)
Property Name	Type	Location	Encumbrances		Original		Costs Capitalized Subsequent to Acquisition	Land and Improvements	Building and Improvements	Land Held for Development	Development and Construction in Progress	Total	Accumulated Depreciation	Year(s) Built/Renovated	Year(s) Acquired	Depreciable Lives (Years)

					Land	Building
Mountain View Research Park	Office	Mountain View, CA	—		95,066	68,373	21,069	95,066	89,442	—	—	184,508	33,095	1977-1981/2007-2013	2013	(1)
Reservoir Place	Office	Waltham, MA	—		18,605	104,124	56,160	20,108	156,954	1,827	—	178,889	90,808	1955/1987/2017	1997/1998	(1)
140 Kendrick Street	Office	Needham, MA	—		18,095	66,905	71,861	19,092	137,769	—	—	156,861	46,586	2000	2004	(1)
1330 Connecticut Avenue	Office	Washington, DC	—		25,982	82,311	39,924	27,135	121,082	—	—	148,217	53,332	1984/2018	2004	(1)
880 Winter Street	Office	Waltham, MA	—		15,597	37,255	95,265	15,597	132,520	—	—	148,117	10,056	1998/2022	2019	(1)
One Freedom Square	Office	Reston, VA	—		9,929	84,504	48,985	11,293	132,125	—	—	143,418	68,406	2000	2003	(1)
Two Freedom Square	Office	Reston, VA	—		13,930	77,739	45,068	15,420	121,317	—	—	136,737	44,662	2001	2003	(1)
Kingstowne Towne Center	Office	Alexandria, VA	—		18,021	109,038	4,665	18,062	113,662	—	—	131,724	54,480	2003-2006	2007	(1)
One and Two Reston Overlook	Office	Reston, VA	—		16,456	66,192	45,224	16,179	111,693	—	—	127,872	61,572	1999	2000	(1)
Shady Grove Innovation District	Office	Rockville, MD	—		52,030	64,212	10,676	26,834	34,954	65,130	—	126,918	4,701	1968-1985	2021	(1)
Weston Corporate Center	Office	Weston, MA	—		25,753	92,312	1,038	25,854	93,249	—	—	119,103	41,485	2010	2001	(1)
355 Main Street	Office	Cambridge, MA	593,545		18,863	53,346	41,772	21,173	92,808	—	—	113,981	36,957	1981/1996/2013	2006	(1)
17Fifty Presidents Street	Office	Reston, VA	—		—	113,362	162	—	113,524	—	—	113,524	16,624	2020	2013	(1)
200 West Street	Office	Waltham, MA	—		16,148	24,983	71,199	16,813	95,160	357	—	112,330	28,192	1999/2021	1997	(1)
Discovery Square	Office	Reston, VA	—		11,198	71,782	21,744	12,533	92,191	—	—	104,724	57,015	2001	2003	(1)
10 CityPoint	Office	Waltham, MA	—		1,953	85,752	7,571	2,288	92,988	—	—	95,276	24,003	2016	1997	(1)
90 Broadway	Office	Cambridge, MA	—	(2)	19,104	52,078	22,742	20,785	73,139	—	—	93,924	31,538	1983/1998/2013	2006	(1)
Waltham Weston Corporate Center	Office	Waltham, MA	—		10,385	60,694	20,705	11,097	80,687	—	—	91,784	45,601	2003	1999	(1)
153 & 211 Second Avenue	Office	Waltham, MA	—		33,233	55,940	718	33,233	55,940	718	—	89,891	6,186	1964-2006	2021	(1)
230 CityPoint	Office	Waltham, MA	—		13,189	49,823	24,297	13,807	73,502	—	—	87,309	40,959	1992	2005	(1)
20 CityPoint	Office	Waltham, MA	—		4,887	72,764	7,072	4,887	79,836	—	—	84,723	13,031	2020	2007	(1)
Sumner Square	Office	Washington, DC	—		624	28,745	51,253	27,837	52,785	—	—	80,622	32,911	1985	1999	(1)
77 CityPoint	Office	Waltham, MA	—		13,847	60,383	1,506	14,023	61,713	—	—	75,736	26,943	2008	2001	(1)
2440 West El Camino Real	Office	Mountain View, CA	—		16,741	51,285	6,565	16,741	57,850	—	—	74,591	21,469	1987/2003	2011	(1)
Wisconsin Place	Office	Chevy Chase, MD	—		—	53,349	13,834	—	67,183	—	—	67,183	28,960	2009	2004	(1)
Reston Corporate Center	Office	Reston, VA	—		9,135	50,857	4,489	10,148	54,333	—	—	64,481	34,194	1984	1998	(1)
255 Main Street	Office	Cambridge, MA	—		134	25,110	33,330	548	58,026	—	—	58,574	43,927	1987	1997	(1)
University Place	Office	Cambridge, MA	—		—	37,091	15,768	4,807	48,052	—	—	52,859	37,130	1985	1998	(1)
890 Winter Street	Office	Waltham, MA	—		13,913	28,557	8,507	13,913	37,064	—	—	50,977	7,296	1999	2019	(1)
Capital Gallery	Office	Washington, DC	—		4,725	29,565	10,361	8,662	35,989	—	—	44,651	23,764	1981/2006	2007	(1)
North First Business Park	Office	San Jose, CA	—		23,398	13,069	5,258	23,378	18,347	—	—	41,725	17,354	1981	2007	(1)
150 Broadway	Office	Cambridge, MA	—		850	25,042	15,749	1,323	40,318	—	—	41,641	18,506	1999	1997	(1)
105 Broadway	Office	Cambridge, MA	—		1,299	12,943	12,723	2,395	24,570	—	—	26,965	16,847	1990	1997	(1)
Lexington Office Park	Office	Lexington, MA	—		998	1,426	19,924	1,263	19,470	1,615	—	22,348	17,200	1982	1997	(1)
The Point	Office	Waltham, MA	—		6,395	10,040	546	6,492	10,489	—	—	16,981	2,638	2015	2007	(1)


Boston Properties, Inc. Schedule 3—Real Estate and Accumulated Depreciation December 31, 2023 (dollars in thousands)
Property Name	Type	Location	Encumbrances			Original				Costs Capitalized Subsequent to Acquisition		Land and Improvements			Building and Improvements			Land Held for Development			Development and Construction in Progress		Total		Accumulated Depreciation		Year(s) Built/Renovated	Year(s) Acquired	Depreciable Lives (Years)

						Land		Building
690 Folsom Street	Office	San Francisco, CA	—			3,219		11,038		1,877		3,219			12,915			—			—		16,134		4,280		2015	2012	(1)
33 Hayden Avenue	Office	Lexington, MA	—			266		3,234		11,502		425			14,577			—			—		15,002		9,090		1979	1997	(1)
Avant Retail	Office	Reston, VA	—			1,499		6,647		2,577		1,499			9,224			—			—		10,723		3,587		2014	2010	(1)
92-100 Hayden Avenue	Office	Lexington, MA	—			594		6,748		1,922		778			8,486			—			—		9,264		7,388		1985	1997	(1)
32 Hartwell Avenue	Office	Lexington, MA	—			168		1,943		6,403		314			8,200			—			—		8,514		2,931		1968/1979/1987	1997	(1)
250 Binney Street	Office	Cambridge, MA	—			110		4,483		3,593		273			7,913						—		8,186		7,244		1983	1997	(1)
453 Ravendale Drive	Office	Mountain View, CA	—			5,477		1,090		1,286		5,477			2,376			—			—		7,853		1,086		1977	2012	(1)
17 Hartwell Avenue	Office	Lexington, MA	—			26		150		6,064		65			6,175						—		6,240		3,755		1968	1997	(1)
The Skylyne	Residential	Oakland, CA	—			28,962		239,077		1,792		28,962			240,869			—			—		269,831		20,181		2020	N/A	(1)
Signature at Reston	Residential	Reston, VA	—			27,076		190,580		3,817		27,076			194,397			—			—		221,473		27,876		2018	2013	(1)
Proto Kendall Square	Residential	Cambridge, MA	—			9,243		127,248		3,336		9,245			130,582			—			—		139,827		17,820		2018	2015	(1)
The Lofts at Atlantic Wharf	Residential	Boston, MA	—			3,529		54,891		2,509		3,529			57,400			—			—		60,929		18,631		2011	2007	(1)
Boston Marriott Cambridge	Hotel	Cambridge, MA	—			478		37,918		32,131		1,201			68,697			629			—		70,527		53,282		1986/2017	1997	(1)
Kendall Center Green Garage	Garage	Cambridge, MA	—		(2)	—		35,035		7,335		103			42,267			—			—		42,370		18,414		1984	2006	(1)
Kendall Center Yellow Garage	Garage	Cambridge, MA	—			1,256		15,697		1,743		1,434			17,262			—			—		18,696		7,857		2006	2004	(1)
290 Binney Street	Development	Cambridge, MA	—			—		—		243,099		1,054			—			—			242,045		243,099		—		N/A	1997	N/A
180 CityPoint	Development	Waltham, MA	—			—		—		214,754		10,908			108,970			—			94,876		214,754		541		N/A	2006	N/A
300 Binney Street	Development	Cambridge, MA	—			18,080		51,262		38,454		18,080			27,805			—			61,911		107,796		6,719		2013	2009	N/A
103 CityPoint	Development	Waltham, MA	—			—		—		88,190		4,672			3,025			8,672			71,821		88,190		18		N/A	2007	N/A
Reston Next Office Phase II	Development	Reston, VA	—			—		—		39,201		—			—			—			39,201		39,201		—		N/A	1998	N/A
Reston Next Retail	Development	Reston, VA	—			—		—		8,367		—			—			—			8,367		8,367		—		N/A	1998	N/A
343 Madison Avenue	Land	New York, NY	—			—		—		206,052		158,885			—			47,167			—		206,052		—		N/A	2023	N/A
777 Harrison Street	Land	San Francisco, CA	—			144,647		—		28,334		—			47			172,934			—		172,981		29		N/A	2020	N/A
Back Bay Station Master Plan	Land	Boston, MA	—			—		—		78,150		—			—			78,150			—		78,150		—		N/A	N/A	N/A
3625-3635 Peterson Way	Land	Santa Clara, CA	—			63,206		—		5,173		—			—			68,379			—		68,379		—		N/A	2016	N/A
Kendall Center Master Plan	Land	Cambridge, MA	—			—		—		48,857		—			—			48,857			—		48,857		—		N/A	1997	N/A
North First Master Plan	Land	San Jose, CA	—			35,004		—		4,068		—			—			39,072			—		39,072		—		N/A	2007	N/A
Plaza at Almaden	Land	San Jose, CA	—			—		—		38,163		—			—			38,163			—		38,163		—		N/A	2006	N/A
CityPoint South Master Plan	Land	Waltham, MA	—			—		—		25,594		—			—			25,594			—		25,594		—		N/A	N/A	N/A
Springfield Metro Center	Land	Springfield, VA	—			—		—		19,896		—			—			19,896			—		19,896		—		N/A	2007	N/A
Reston Gateway Master Plan	Land	Reston, VA	—			—		—		13,908		—			—			13,908			—		13,908		—		N/A	1998	N/A
Weston Quarry	Land	Weston, MA	—			—		—		1,249		—			—			1,249			—		1,249		—		N/A	2001	N/A
Broad Run Business Park	Land	Loudoun County, VA	—			—		—		1,186		—			—			1,186			—		1,186		—		N/A	1998	N/A
Reston Overlook Master Plan	Land	Reston, VA	—			—		—		80		—			—			80			—		80		—		N/A	2000	N/A

			$	4,166,379	(3)	$	5,637,035	$	15,478,086	$	6,306,350	$	5,953,798	(4)	$	20,223,332	(5)	$	697,061	(6)	$	547,280	$	27,421,471	$	6,841,404

Note: Total Real Estate does not include Furniture, Fixtures and Equipment totaling approximately $53,716. Accumulated Depreciation does not include approximately $40,324 of accumulated depreciation related to Furniture, Fixtures and Equipment. Office type includes office, life sciences, and retail properties.

The aggregate cost and accumulated depreciation for tax purposes was approximately $25.2 billion and $5.9 billion, respectively.

(1)Depreciation of the buildings and improvements are calculated over lives ranging from the life of the lease to 40 years.

(2)This property is encumbered with the mortgage note shown at 355 Main Street. See Note 7 to the Consolidated Financial Statements.

(3)Includes unamortized deferred financing costs and fair value debt adjustment totaling approximately $(33.6) million.

(4)Includes Right of Use Assets - Finance Leases and Right of Use Assets - Operating Leases of approximately $378,276 and $324,298, respectively.

(5)Includes Right of Use Assets - Finance Leases of approximately $23,404.

(6)Includes pre-development costs.

Boston Properties, Inc.

Real Estate and Accumulated Depreciation

December 31, 2023, 2022 and 2021

(dollars in thousands)

A summary of activity for real estate and accumulated depreciation is as follows:


	2023		2022		2021
Real Estate:
Balance at the beginning of the year	$	25,744,214	$	24,108,220	$	23,303,303
Additions to/improvements of real estate	1,811,036		2,228,000		1,145,084
Assets sold/written-off	(133,779)		(592,006)		(340,167)
Balance at the end of the year	$	27,421,471	$	25,744,214	$	24,108,220
Accumulated Depreciation:
Balance at the beginning of the year	$	6,260,992	$	5,848,183	$	5,501,637
Depreciation expense	714,191		646,020		623,854
Assets sold/written-off	(133,779)		(233,211)		(277,308)
Balance at the end of the year	$	6,841,404	$	6,260,992	$	5,848,183

Note: Real Estate and Accumulated Depreciation amounts do not include Furniture, Fixtures and Equipment.


Boston Properties Limited Partnership Schedule 3—Real Estate and Accumulated Depreciation December 31, 2023 (dollars in thousands)
						Original				Costs Capitalized Subsequent to Acquisition		Land and Improvements		Building and Improvements		Land Held for Development		Development and Construction in Progress		Total		Accumulated Depreciation		Year(s) Built/Renovated	Year(s) Acquired	Depreciable Lives (Years)
Property Name	Type	Location	Encumbrances			Land		Building
767 Fifth Avenue (the General Motors Building)	Office	New York, NY	$	2,288,004		$	1,796,252	$	1,532,654	$	365,829	$	1,796,252	$	1,898,483	$	—	$	—	$	3,694,735	$	507,660	1968/2019	2013	(1)
Prudential Center	Office	Boston, MA	—			92,077		948,357		732,224		100,535		1,643,064		—		29,059		1,772,658		754,356		1965/1993/2002/2016-2017	1998/1999/2000	(1)
Embarcadero Center	Office	San Francisco, CA	—			179,697		847,410		462,102		180,419		1,308,790		—		—		1,489,209		760,144		1970/1989	1998-1999	(1)
399 Park Avenue	Office	New York, NY	—			339,200		700,358		349,238		339,200		1,049,596		—		—		1,388,796		462,543		1961/2018	2002	(1)
601 Lexington Avenue	Office	New York, NY	989,181			241,600		494,782		508,526		279,281		965,627		—		—		1,244,908		360,656		1977/1997/2021	2001	(1)
Salesforce Tower	Office	San Francisco, CA	—			200,349		946,205		7,623		200,349		953,828		—		—		1,154,177		159,274		2018	2013	(1)
200 Clarendon Street and Garage	Office	Boston, MA	—			219,543		667,884		251,372		250,910		887,889		—		—		1,138,799		338,529		1976	2010	(1)
250 West 55th Street	Office	New York, NY	—			285,263		603,167		52,917		285,263		656,084		—		—		941,347		198,081		2014	2007	(1)
100 Federal Street	Office	Boston, MA	—			131,067		435,954		127,199		131,067		563,153		—		—		694,220		172,079		1971-1975/2017	2012	(1)
Madison Centre	Office	Seattle, WA	—			104,641		564,336		4,082		104,641		568,418						673,059		35,516		2017	2022	(1)
Times Square Tower	Office	New York, NY	—			165,413		380,438		102,302		159,694		488,459		—		—		648,153		244,067		2004	2000	(1)
Carnegie Center	Office	Princeton, NJ	—			142,666		316,856		162,582		90,501		472,803		58,800		—		622,104		262,096		1983-2016	1998/1999/2000/2007/2014/2017/2019	(1)
Santa Monica Business Park	Office	Los Angeles, CA	295,649			46,360		410,421		164,229		210,471		410,535		4		—		621,010		865		1976-1980	2023	(1)
125 Broadway	Office	Cambridge, MA	—			126,364		433,662		4,000		126,364		437,662		—		—		564,026		20,717		2000	2022	(1)
Reston Next	Office	Reston, VA	—			35,549		525,277		—		2,901		557,925		—		—		560,826		32,504		2022	1998	(1)
Atlantic Wharf	Office	Boston, MA	—			63,988		454,537		39,399		63,988		493,936		—		—		557,924		180,686		2011	2007	(1)
2100 Pennsylvania Avenue	Office	Washington, DC	—			185,203		324,206		—		185,203		324,206		—		—		509,409		20,768		2023	N/A	(1)
Fountain Square	Office	Reston, VA	—			56,853		306,298		49,874		56,853		356,172		—		—		413,025		111,481		1986-1990	2012	(1)
599 Lexington Avenue	Office	New York, NY	—			81,040		100,507		231,417		81,040		331,924		—		—		412,964		188,193		1986	1997	(1)
510 Madison Avenue	Office	New York, NY	—			103,000		253,665		33,100		103,000		286,765		—		—		389,765		104,052		2012	2010	(1)
325 Main Street	Office	Cambridge, MA	—		(2)	21,596		312,492		30,740		21,403		343,425		—		—		364,828		14,833		2022	1997	(1)
680 Folsom Street	Office	San Francisco, CA	—			72,545		219,766		8,026		72,545		227,792		—		—		300,337		80,964		2014	2012	(1)
145 Broadway	Office	Cambridge, MA	—			121		273,013		26,156		23,164		276,126		—		—		299,290		35,390		2019	1997	(1)
2200 Pennsylvania Avenue	Office	Washington, DC	—			—		183,541		114,090		102,979		194,652		—		—		297,631		77,357		2011	2008	(1)
South of Market and Democracy Tower	Office	Reston, VA	—			13,603		237,479		30,616		13,603		268,095		—		—		281,698		108,875		2008-2009	2003	(1)
Bay Colony Corporate Center	Office	Waltham, MA	—			18,789		148,451		96,639		18,789		240,416		4,674		—		263,879		113,123		1985-1989	2011	(1)
535 Mission Street	Office	San Francisco, CA	—			40,933		148,378		4,629		40,934		153,006		—		—		193,940		46,615		2015	2013	(1)
Mountain View Research Park	Office	Mountain View, CA	—			95,066		68,373		21,069		95,066		89,442		—		—		184,508		33,095		1977-1981/2007-2013	2013	(1)
Reservoir Place	Office	Waltham, MA	—			18,605		104,124		52,085		19,089		153,898		1,827		—		174,814		89,426		1955/1987/2017	1997/1998	(1)
140 Kendrick Street	Office	Needham, MA	—			18,095		66,905		67,871		18,095		134,776		—		—		152,871		45,233		2000	2004	(1)
880 Winter Street	Office	Waltham, MA	—			15,597		37,255		95,265		15,597		132,520		—		—		148,117		10,056		1998/2022	2019	(1)


Boston Properties Limited Partnership Schedule 3—Real Estate and Accumulated Depreciation December 31, 2023 (dollars in thousands)
					Original		Costs Capitalized Subsequent to Acquisition	Land and Improvements	Building and Improvements	Land Held for Development	Development and Construction in Progress	Total	Accumulated Depreciation	Year(s) Built/Renovated	Year(s) Acquired	Depreciable Lives (Years)
Property Name	Type	Location	Encumbrances		Land	Building
1330 Connecticut Avenue	Office	Washington, DC	—		25,982	82,311	35,311	25,982	117,622	—	—	143,604	51,767	1984/2018	2004	(1)
One Freedom Square	Office	Reston, VA	—		9,929	84,504	43,348	9,883	127,898	—	—	137,781	66,495	2000	2003	(1)
Kingstowne Towne Center	Office	Alexandria, VA	—		18,021	109,038	4,501	18,021	113,539	—	—	131,560	54,432	2003-2006	2007	(1)
Two Freedom Square	Office	Reston, VA	—		13,930	77,739	38,856	13,866	116,659	—	—	130,525	42,556	2001	2003	(1)
Shady Grove Innovation District	Office	Rockville, MD	—		52,030	64,212	10,676	26,834	34,954	65,130	—	126,918	4,701	1968-1985	2021	(1)
One and Two Reston Overlook	Office	Reston, VA	—		16,456	66,192	40,806	15,074	108,380	—	—	123,454	60,074	1999	2000	(1)
Weston Corporate Center	Office	Weston, MA	—		25,753	92,312	1,038	25,854	93,249	—	—	119,103	41,485	2010	2001	(1)
355 Main Street	Office	Cambridge, MA	593,545		18,863	53,346	41,474	21,098	92,585	—	—	113,683	36,858	1981/1996/2013	2006	(1)
17Fifty Presidents Street	Office	Reston, VA	—		—	113,362	162	—	113,524	—	—	113,524	16,624	2020	2013	(1)
200 West Street	Office	Waltham, MA	—		16,148	24,983	68,538	16,148	93,164	357	—	109,669	27,290	1999/2021	1997	(1)
Discovery Square	Office	Reston, VA	—		11,198	71,782	16,199	11,146	88,033	—	—	99,179	55,135	2001	2003	(1)
10 CityPoint	Office	Waltham, MA	—		1,953	85,752	7,410	2,127	92,988	—	—	95,115	24,003	2016	1997	(1)
90 Broadway	Office	Cambridge, MA	—	(2)	19,104	52,078	22,563	20,741	73,004	—	—	93,745	31,484	1983/1998/2013	2006	(1)
153 & 211 Second Avenue	Office	Waltham, MA	—		33,233	55,940	718	33,233	55,940	718	—	89,891	6,186	1964-2006	2021	(1)
Waltham Weston Corporate Center	Office	Waltham, MA	—		10,385	60,694	17,718	10,350	78,447	—	—	88,797	44,588	2003	1999	(1)
230 CityPoint	Office	Waltham, MA	—		13,189	49,823	22,680	13,403	72,289	—	—	85,692	40,413	1992	2005	(1)
20 CityPoint	Office	Waltham, MA	—		4,887	72,764	7,072	4,887	79,836	—	—	84,723	13,031	2020	2007	(1)
Sumner Square	Office	Washington, DC	—		624	28,745	49,173	27,317	51,225	—	—	78,542	32,209	1985	1999	(1)
77 CityPoint	Office	Waltham, MA	—		13,847	60,383	1,401	13,997	61,634	—	—	75,631	26,911	2008	2001	(1)
2440 West El Camino Real	Office	Mountain View, CA	—		16,741	51,285	6,565	16,741	57,850	—	—	74,591	21,469	1987/2003	2011	(1)
Wisconsin Place	Office	Chevy Chase, MD	—		—	53,349	13,834	—	67,183	—	—	67,183	28,960	2009	2004	(1)
Reston Corporate Center	Office	Reston, VA	—		9,135	50,857	1,878	9,496	52,374	—	—	61,870	33,309	1984	1998	(1)
255 Main Street	Office	Cambridge, MA	—		134	25,110	31,674	134	56,784	—	—	56,918	43,368	1987	1997	(1)
University Place	Office	Cambridge, MA	—		—	37,091	14,318	4,807	46,602	—	—	51,409	36,037	1985	1998	(1)
890 Winter Street	Office	Waltham, MA	—		13,913	28,557	8,507	13,913	37,064	—	—	50,977	7,296	1999	2019	(1)
North First Business Park	Office	San Jose, CA	—		23,398	13,069	5,235	23,372	18,330	—	—	41,702	17,347	1981	2007	(1)
Capital Gallery	Office	Washington, DC	—		4,725	29,565	5,698	6,128	33,860	—	—	39,988	22,801	1981/2006	2007	(1)
150 Broadway	Office	Cambridge, MA	—		850	25,042	13,744	822	38,814	—	—	39,636	17,823	1999	1997	(1)
105 Broadway	Office	Cambridge, MA	—		1,299	12,943	10,617	1,868	22,991	—	—	24,859	16,133	1990	1997	(1)
Lexington Office Park	Office	Lexington, MA	—		998	1,426	19,160	1,072	18,897	1,615	—	21,584	16,945	1982	1997	(1)
The Point	Office	Waltham, MA	—		6,395	10,040	546	6,492	10,489	—	—	16,981	2,638	2015	2007	(1)
690 Folsom Street	Office	San Francisco, CA	—		3,219	11,038	1,877	3,219	12,915	—	—	16,134	4,280	2015	2012	(1)
33 Hayden Avenue	Office	Lexington, MA	—		266	3,234	10,865	266	14,099	—	—	14,365	8,873	1979	1997	(1)
Avant Retail	Office	Reston, VA	—		1,499	6,647	2,577	1,499	9,224	—	—	10,723	3,587	2014	2010	(1)
92-100 Hayden Avenue	Office	Lexington, MA	—		594	6,748	1,193	595	7,940	—	—	8,535	7,140	1985	1997	(1)


Boston Properties Limited Partnership Schedule 3—Real Estate and Accumulated Depreciation December 31, 2023 (dollars in thousands)
						Original				Costs Capitalized Subsequent to Acquisition		Land and Improvements			Building and Improvements			Land Held for Development			Development and Construction in Progress		Total		Accumulated Depreciation		Year(s) Built/Renovated	Year(s) Acquired	Depreciable Lives (Years)
Property Name	Type	Location	Encumbrances			Land		Building
32 Hartwell Avenue	Office	Lexington, MA	—			168		1,943		5,817		168			7,760			—			—		7,928		2,731		1968/1979/1987	1997	(1)
453 Ravendale Drive	Office	Mountain View, CA	—			5,477		1,090		1,286		5,477			2,376			—			—		7,853		1,086		1977	2012	(1)
250 Binney Street	Office	Cambridge, MA	—			110		4,483		2,939		110			7,422						—		7,532		7,026		1983	1997	(1)
17 Hartwell Avenue	Office	Lexington, MA	—			26		150		5,907		26			6,057			—			—		6,083		3,701		1968	1997	(1)
The Skylyne	Residential	Oakland, CA	—			28,962		239,077		1,792		28,962			240,869			—			—		269,831		20,181		2020	N/A	(1)
Signature at Reston	Residential	Reston, VA	—			27,076		190,580		3,817		27,076			194,397			—			—		221,473		27,876		2018	2013	(1)
Proto Kendall Square	Residential	Cambridge, MA	—			9,243		127,248		3,336		9,245			130,582			—			—		139,827		17,820		2018	2015	(1)
The Lofts at Atlantic Wharf	Residential	Boston, MA	—			3,529		54,891		2,509		3,529			57,400			—			—		60,929		18,631		2011	2007	(1)
Boston Marriott Cambridge	Hotel	Cambridge, MA	—			478		37,918		29,240		478			66,529			629			—		67,636		52,302		1986/2017	1997	(1)
Kendall Center Green Garage	Garage	Cambridge, MA	—		(2)	—		35,035		6,921		—			41,956			—			—		41,956		18,275		1984	2006	(1)
Kendall Center Yellow Garage	Garage	Cambridge, MA	—			1,256		15,697		1,031		1,256			16,728			—			—		17,984		7,619		2006	2004	(1)
290 Binney Street	Development	Cambridge, MA	—			—		—		242,683		638			—			—			242,045		242,683		—		N/A	1997	N/A
180 CityPoint	Development	Waltham, MA	—			—		—		214,754		10,908			108,970			—			94,876		214,754		541		N/A	2006	N/A
300 Binney Street	Development	Cambridge, MA	—			18,080		51,262		38,454		18,080			27,805			—			61,911		107,796		6,719		2013	2009	N/A
103 CityPoint	Development	Waltham, MA	—			—		—		88,188		4,670			3,025			8,672			71,821		88,188		18		N/A	2007	N/A
Reston Next Office Phase II	Development	Reston, VA	—			—		—		39,201		—			—			—			39,201		39,201		—		N/A	1998	N/A
Reston Next Retail	Development	Reston, VA	—			—		—		8,367		—			—			—			8,367		8,367		—		N/A	1998	N/A
343 Madison Avenue	Land	New York, NY	—			—		—		206,052		158,885			—			47,167			—		206,052		—		N/A	2023	N/A
777 Harrison Street	Land	San Francisco, CA	—			144,647		—		28,334		—			47			172,934			—		172,981		29		N/A	2020	N/A
Back Bay Station Master Plan	Land	Boston, MA	—			—		—		78,150		—			—			78,150			—		78,150		—		N/A	N/A	N/A
3625-3635 Peterson Way	Land	Santa Clara, CA	—			63,206		—		5,173		—			—			68,379			—		68,379		—		N/A	2016	N/A
Kendall Center Master Plan	Land	Cambridge, MA	—			—		—		48,857		—			—			48,857			—		48,857		—		N/A	1997	N/A
North First Master Plan	Land	San Jose, CA	—			35,004		—		4,068		—			—			39,072			—		39,072		—		N/A	2007	N/A
Plaza at Almaden	Land	San Jose, CA	—			—		—		38,163		—			—			38,163			—		38,163		—		N/A	2006	N/A
CityPoint South Master Plan	Land	Waltham, MA	—			—		—		25,594		—			—			25,594			—		25,594		—		N/A	N/A	N/A
Springfield Metro Center	Land	Springfield, VA	—			—		—		19,896		—			—			19,896			—		19,896		—		N/A	2007	N/A
Reston Gateway Master Plan	Land	Reston, VA	—			—		—		13,908		—			—			13,908			—		13,908		—		N/A	1998	N/A
Weston Quarry	Land	Weston, MA	—			—		—		1,249		—			—			1,249			—		1,249		—		N/A	2001	N/A
Broad Run Business Park	Land	Loudoun County, VA	—			—		—		1,186		—			—			1,186			—		1,186		—		N/A	1998	N/A
Reston Overlook Master Plan	Land	Reston, VA	—			—		—		80		—			—			80			—		80		—		N/A	2000	N/A

			$	4,166,379	(3)	$	5,637,035	$	15,478,086	$	5,940,085	$	5,859,089	(4)	$	19,951,776	(5)	$	697,061	(6)	$	547,280	$	27,055,206	$	6,718,037

The aggregate cost and accumulated depreciation for tax purposes was approximately $28.2 billion and $6.6 billion, respectively.

(1)Depreciation of the buildings and improvements are calculated over lives ranging from the life of the lease to 40 years.

(2)This property is encumbered with the mortgage note shown at 355 Main Street. See Note 7 to the Consolidated Financial Statements.

(3)Includes unamortized deferred financing costs and fair value debt adjustment totaling approximately $(33.6) million.

(4)Includes Right of Use Assets - Finance Leases and Right of Use Assets - Operating Leases of approximately $378,276 and $324,298, respectively.

(5)Includes Right of Use Assets - Finance Leases of approximately $23,404.

(6)Includes pre-development costs.

Boston Properties Limited Partnership

Real Estate and Accumulated Depreciation

December 31, 2023, 2022 and 2021

(dollars in thousands)

A summary of activity for real estate and accumulated depreciation is as follows:


	2023		2022		2021
Real Estate:
Balance at the beginning of the year	$	25,376,700	$	23,734,833	$	22,926,494
Additions to/improvements of real estate	1,811,036		2,228,000		1,145,084
Assets sold/written-off	(132,530)		(586,133)		(336,745)
Balance at the end of the year	$	27,055,206	$	25,376,700	$	23,734,833
Accumulated Depreciation:
Balance at the beginning of the year	$	6,143,384	$	5,736,240	$	5,396,111
Depreciation expense	707,183		638,538		615,553
Assets sold/written-off	(132,530)		(231,394)		(275,424)
Balance at the end of the year	$	6,718,037	$	6,143,384	$	5,736,240

Note: Real Estate and Accumulated Depreciation amounts do not include Furniture, Fixtures and Equipment.

Noncontrolling Interests (Property Partnerships) (Narrative) (Details) $ in Thousands			1 Months Ended	12 Months Ended
	Nov. 13, 2023 USD ($) Buildings	Jul. 28, 2023 USD ($)	Dec. 31, 2023 USD ($) Real_Estate_Properties	Dec. 31, 2023 USD ($) Real_Estate_Properties	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)
Noncontrolling Interest [Line Items]
Noncontrolling Interest in Limited Partnerships			$ 1,640,704	$ 1,640,704	$ 1,547,317
Contribution of Property				17,519	0	$ 0
Proceeds from sale of interest in property partnerships and contributions from noncontrolling interests in property partnerships				$ 244,541	$ 849	$ 18,002
Construction in Progress
Noncontrolling Interest [Line Items]
Number of real estate properties \| Real_Estate_Properties			10	10
Noncontrolling Interest [Member] \| 343 Madison Avenue
Noncontrolling Interest [Line Items]
Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners		45.00%
Parent \| 343 Madison Avenue
Noncontrolling Interest [Line Items]
Noncontrolling Interest, Ownership Percentage by Parent		55.00%
343 Madison Avenue \| Noncontrolling Interest [Member]
Noncontrolling Interest [Line Items]
Payments to Acquire Investments		$ 4,800
Contribution of Property		17,500
343 Madison Avenue \| Parent
Noncontrolling Interest [Line Items]
Payments to Acquire Investments		5,900
Contribution of Property		$ 21,400
300 Binney and 290 Binney \| Construction in Progress
Noncontrolling Interest [Line Items]
Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners	45.00%
Number of real estate properties \| Buildings	2
300 Binney Street
Noncontrolling Interest [Line Items]
Proceeds from sale of interest in property partnerships and contributions from noncontrolling interests in property partnerships	$ 212,900
Noncontrolling Interest, Increase from Sale of Parent Equity Interest	35,500		$ 17,000
Difference Between Proceeds from Sale and Noncontrolling Interest	$ 177,400
300 Binney Street \| Noncontrolling Interest [Member]
Noncontrolling Interest [Line Items]
Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners	45.00%
Noncontrolling Interest, Ownership Percentage by Parent	55.00%

Investments in Unconsolidated Joint Ventures (Investments in Unconsolidated Joint Ventures) (Details) - USD ($)
$ in Thousands

12 Months Ended

Jan. 08, 2024

Dec. 31, 2023

Dec. 14, 2023

Dec. 31, 2022

Schedule of Equity Method Investments [Line Items]

$ (445,947)

$ (450,918)

Investments In Affiliates Subsidiaries Associates And Joint Ventures net

1,377,319

1,715,911

^[1]

1,337,416

1,630,485

Schedule of Equity Method Investments [Line Items]

Square 407 Limited Partnership [Member]

$ (39,900)

(85,400)

Schedule of Equity Method Investments [Line Items]

Market Square North

50.00%

BP/CRF Metropolitan Square LLC [Member]

^[1]

$ (5,996)

$ (6,198)

Schedule of Equity Method Investments [Line Items]

Metropolitan Square

^[2]

20.00%

901 New York Avenue LLC [Member]

^[1]

$ (37,629)

Schedule of Equity Method Investments [Line Items]

901 New York Avenue

^[3]

25.00%

901 New York Avenue LLC (economic ownership) [Member]

^[1]

$ (11,764)

$ (12,493)

Schedule of Equity Method Investments [Line Items]

WP Project Developer LLC [Member]

50.00%

Schedule of Equity Method Investments [Line Items]

Wisconsin Place Land and Infrastructure

^[4]

33.33%

500 North Capitol Venture LLC [Member]

^[1]

$ 30,375

$ 31,971

Schedule of Equity Method Investments [Line Items]

500 North Capitol Street, NW

30.00%

501 K Street LLC [Member]

^[1]

$ (10,253)

(9,185)

Schedule of Equity Method Investments [Line Items]

1001 6th Street

50.00%

Podium Developer LLC [Member]

^[1]

$ 44,774

42,922

Schedule of Equity Method Investments [Line Items]

The Hub on Causeway - Podium

50.00%

Residential Tower Developer LLC [Member]

^[1]

$ 45,201

46,839

Schedule of Equity Method Investments [Line Items]

Hub50House

50.00%

Hotel Tower Developer LLC [Member]

^[1]

$ 40,235

45,414

Schedule of Equity Method Investments [Line Items]

The Hub on Causeway - Hotel Air Rights

50.00%

Office Tower Developer LLC

^[1]

$ 13,494

12,366

Schedule of Equity Method Investments [Line Items]

100 Causeway Street

50.00%

1265 Main Office JV LLC [Member]

^[1]

$ 57,660

59,716

Schedule of Equity Method Investments [Line Items]

1265 Main Street

50.00%

BNY Tower Holdings LLC [Member]

^[1]

$ 3,585

3,465

Schedule of Equity Method Investments [Line Items]

Dock 72

^[5]

50.00%

CA-Colorado Center LLC[Member]

^[1]

$ (11,890)

(19,921)

Schedule of Equity Method Investments [Line Items]

Colorado Center

50.00%

7750 Wisconsin Avenue LLC [Member]

^[1]

$ 237,815

233,862

Schedule of Equity Method Investments [Line Items]

7750 Wisconsin Avenue

50.00%

BP-M 3HB Venture LLC [Member]

^[1]

$ 50,064

52,152

Schedule of Equity Method Investments [Line Items]

3 Hudson Boulevard

25.00%

Schedule of Equity Method Investments [Line Items]

^[1]

$ 115,103

$ 116,397

SMBP Venture LP [Member]

Santa Monica Business Park

^[6]

55.00%

SMBP Venture LP [Member] | Joint Venture Partner [Member]

^[1]

$ 164,735

Schedule of Equity Method Investments [Line Items]

Platform 16 Holdings LP [Member]

45.00%

Schedule of Equity Method Investments [Line Items]

Platform 16

^[7],[8]

55.00%

Gateway Portfolio Holdings LLC [Member]

^[1]

$ 45,564

158,109

Schedule of Equity Method Investments [Line Items]

Gateway Commons

50.00%

Rosecrans-Sepulveda Partners 4, LLC

^[1]

$ 376,834

324,038

Schedule of Equity Method Investments [Line Items]

Beach Cities Media Campus

50.00%

^[1]

$ 27,034

27,000

Schedule of Equity Method Investments [Line Items]

Safeco Plaza

^[8],[9]

33.67%

Safeco Plaza REIT LLC | Company's Share [Member]

^[1]

$ 44,734

69,785

Schedule of Equity Method Investments [Line Items]

33.00%

Schedule of Equity Method Investments [Line Items]

360 Park Avenue South

^[8],[10]

71.11%

Number of Promote Entities

$ 42,988

$ 114,992

^[1]

Payments to Acquire Real Estate and Real Estate Joint Ventures

$ 10,000

360 PAS Holdco LLC | Company's Share [Member]

Schedule of Equity Method Investments [Line Items]

360 PAS Holdco LLC | Joint Venture Partner [Member] | Scenario, Plan

35.79%

Schedule of Equity Method Investments [Line Items]

PR II BXP Reston Gateway LLC

29.00%

Schedule of Equity Method Investments [Line Items]

Skymark - Reston Next Residential

20.00%

Schedule of Equity Method Investments [Line Items]

^[1]

$ 15,184

$ 11,351

751 Gateway Holdings LLC

751 Gateway

49.00%

^[1]

$ 93,411

80,714

Schedule of Equity Method Investments [Line Items]

200 Fifth Avenue

^[8]

26.69%

ABXP Worldgate Investments LLC

^[1]

$ 75,718

$ 120,083

Schedule of Equity Method Investments [Line Items]

13100 and 13150 Worldgate Drive

50.00%

Entity Owning Land And Infrastructure Of Project [Member]

^[1]

$ 17,546

Schedule of Equity Method Investments [Line Items]

Safeco Partner Entity One [Member] | Company's Share [Member]

33.33%

Schedule of Equity Method Investments [Line Items]

Safeco Partner Entity Two | Company's Share [Member]

1.00%

Schedule of Equity Method Investments [Line Items]

360 Park Avenue South Partners Entity | Company's Share [Member]

1.00%

Schedule of Equity Method Investments [Line Items]

360 Park Avenue South Partners Entity Two | Company's Share [Member]

1.00%

Schedule of Equity Method Investments [Line Items]

360 PAS Holdco LLC (indirect ownership)

1.00%

Schedule of Equity Method Investments [Line Items]

Number of joint venture partner(s)

360 PAS Holdco LLC (indirect ownership) | Company's Share [Member]

Schedule of Equity Method Investments [Line Items]

Debt Disclosure [Text Block]

35.02%

5.837%

[1]	Investments with deficit balances aggregating approximately $39.9 million and $85.4 million at December 31, 2023 and December 31, 2022, respectively, are included within Other Liabilities in the Company’s Consolidated Balance Sheets.
[2]	During the year ended December 31, 2023, the Company completed a restructuring of its ownership in Metropolitan Square, as described below in this Note 6.
[3]	The Company’s economic ownership increased based on the achievement of certain return thresholds. At December 31, 2023 and December 31, 2022, the Company’s economic ownership was approximately 50%. On January 8, 2024, the Company’s joint venture partner transferred all of its interest in the joint venture to the Company for a gross purchase price of $10.0 million, see Note 17 for more information.
[4]	The Company’s wholly-owned subsidiary that owns Wisconsin Place Office also owns a 33.33% interest in the joint venture entity that owns the land, parking garage and infrastructure of the project.
[5]	This property includes net equity balances from the amenity joint venture.
[6]	During the year ended December 31, 2023, the Company completed the acquisition of its joint venture partner’s 45% ownership interest in Santa Monica Business Park, as described below in this Note 6 and Note 3.
[7]	At December 31, 2022, this entity was a VIE.
[8]	During the year ended December 31, 2023, the Company recognized an other-than-temporary impairment loss on its investment.
[9]	The Company’s ownership includes (1) a 33.0% direct interest in the joint venture, and (2) an additional 1% interest in each of the two entities through which each partner owns its interest in the joint venture.
[10]	On December 14, 2023, the Company completed the acquisition of all of one of its joint venture partners ownership interest. As a result of this acquisition, at December 31, 2023, the Company’s ownership includes (1) a 35.79% direct interest in the joint venture, (2) an additional 35.02% indirect ownership in the joint venture, and (3) an additional 1% interest in the entity through which the partner owns its interest in the joint venture. The Company’s partner will fund required capital until its aggregate investment is approximately 29% of all capital contributions; thereafter, the partners will fund required capital according to their percentage interests. At December 31, 2022, the Company’s ownership included (1) a 35.79% direct interest in the joint venture, (2) an additional 5.837% indirect ownership in the joint venture, and (3) an additional 1% interest in each of the two entities through which each partner owns its interest in the joint venture.

Employee Benefits Plan	12 Months Ended
Employee Benefits Plan	Dec. 31, 2023
Disclosure Text Block Supplement [Abstract]
Employee Benefit Plans	14. Employee Benefit Plans Effective January 1, 1985, the predecessor of the Company adopted a 401(k) Savings Plan (the “Plan”) for its employees. Upon formation, the Company adopted the Plan and the terms of the Plan. Under the Plan, as amended, the Company’s matching contribution equals 200% of the first 3% of participant’s eligible earnings contributed (utilizing earnings that are not in excess of an amount established by the IRS ($330,000, $305,000 and $290,000 in 2023, 2022 and 2021, respectively), indexed for inflation) with no vesting requirement. The Company’s aggregate matching contribution for the years ended December 31, 2023, 2022 and 2021 was approximately $5.4 million, $4.8 million and $4.7 million, respectively. The Company also maintains a deferred compensation plan that is designed to allow officers of BXP to defer a portion of the officer’s current income on a pre-tax basis and receive a tax-deferred return on these deferrals based on the performance of specific investments selected by the officer. The Company’s obligation under the plan is that of an unsecured promise to pay the deferred compensation to the plan participants in the future. At December 31, 2023 and 2022, the Company had maintained approximately $35.3 million and $31.7 million, respectively, in a separate account, which is not restricted as to its use. The Company’s liability under the plan is equal to the total amount of compensation deferred by the plan participants and earnings on the deferred compensation pursuant to investments elected by the plan participants. The Company’s liability as of December 31, 2023 and 2022 was approximately $35.3 million and $31.7 million, respectively, which are included in the accompanying Consolidated Balance Sheets.

Unsecured Credit Facility (Details) $ in Thousands	Dec. 31, 2023 USD ($)	Jun. 01, 2023	Jun. 15, 2021 USD ($)	Sep. 28, 2023 USD ($)	Dec. 31, 2022 USD ($)
Line of Credit Facility [Line Items]
Line of Credit Facility, Expiration Date			Jun. 15, 2026
Line of Credit Facility, Interest Rate Reduction			0.01%
Line of credit facility, maximum percent for loan advances			65.00%
Debt Instrument, Alternate Basis Spread on Variable Rate	0.00%
Long-term Line of Credit	$ 0				$ 0
Maximum [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Commitment Fee Percentage			0.30%
Line of Credit Facility, Unused Capacity, Commitment Fee Percentage			1.40%
Minimum [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Commitment Fee Percentage			0.10%
Line of Credit Facility, Unused Capacity, Commitment Fee Percentage			0.70%
Revolving Credit Facility [Member]
Line of Credit Facility [Line Items]
Debt Instrument, Basis Spread on Variable Rate	0.775%
Line of Credit Facility, Maximum Borrowing Capacity			$ 1,500,000	$ 1,815,000
Line of Credit, Additional Borrowing Capacity			$ 500,000
Line of Credit Borrowing Capacity Increase (Decrease)				$ 315,000
Line of Credit Facility, Interest Rate Description			At BPLP’s option, loans under the 2021 Credit Facility will bear interest at a rate per annum equal to (1) (a) in the case of loans denominated in Dollars, Term SOFR and SOFR, (b) in the case of loans denominated in Euro, EURIBOR, (c) in the case of loans denominated in Canadian Dollars, CDOR, and (d) in the case of loans denominated in Sterling, SONIA, in each case, plus a margin ranging from 70.0 to 140.0 basis points based on BPLP’s credit rating or (2) an alternate base rate equal to the greatest of (a) the Federal Funds rate plus 0.5%, (b) the administrative agent’s prime rate, (c) Term SOFR plus 1.00%, and (d) 1.00%, in each case, plus a margin ranging from 0 to 40 basis points based on BPLP’s credit rating.
Line of Credit Facility, Commitment Fee Percentage	0.15%
Long-term Line of Credit	$ 0				$ 0
Number of Lenders				3
Revolving Credit Facility [Member] \| Base Rate [Member]
Line of Credit Facility [Line Items]
Debt Instrument, Basis Spread on Variable Rate		0.10%

Debt

12 Months Ended

Dec. 31, 2023

Debt Disclosure [Abstract]

7. Debt

Mortgage Notes Payable

The Company had outstanding mortgage notes payable totaling approximately $4.2 billion and $3.3 billion as of December 31, 2023 and 2022, respectively, each collateralized by one or more buildings and related land included in real estate assets. The mortgage notes payable are generally due in monthly installments and mature at various dates through January 9, 2032.

Including the effects of interest rate swaps, there were no variable rate mortgage loans at December 31, 2023 and 2022 (see Note 8). Therefore, fixed rate mortgage notes payable totaled approximately $4.2 billion and $3.3 billion at December 31, 2023 and 2022, respectively, with contractual interest rates ranging from 2.79% to 6.04% per annum at December 31, 2023 and 2.79% to 3.43% per annum at December 31, 2022 (with a weighted-average interest rate of 3.70% and 3.24% at December 31, 2023 and 2022, respectively).

Contractual aggregate principal payments of mortgage notes payable at December 31, 2023 are as follows (dollars in thousands):


	Principal Payments
2024	$	—
2025	300,000
2026	—
2027	2,300,000
2028	600,000
Thereafter	1,000,000
Total aggregate principal payments	4,200,000
Less:
Deferred financing costs, net	29,270
Fair value debt adjustment	4,351
Total carrying value of mortgage notes payable, net	$	4,166,379

On October 26, 2023, the Company closed on a mortgage loan collateralized by its 325 Main Street, 355 Main Street, 90 Broadway and Cambridge East Garage (also known as Kendall Center Green Garage) properties located in Cambridge, Massachusetts. The mortgage loan has a principal amount of $600.0 million, bears interest at a variable rate of Daily Compounded SOFR plus 2.25% per annum and matures on October 26, 2028 (See Note 8). The loan requires monthly interest-only payments during the term of the loan, with the entire principal amount due at maturity. 325 Main Street, 355 Main Street and 90 Broadway are three premier workplaces that aggregate approximately 898,000 net rentable square feet.

On December 14, 2023, the Company completed the acquisition of its joint venture partner’s 45% interest in the joint venture entity that owns Santa Monica Business Park located in Santa Monica, California (See Note 3). The property is subject to existing mortgage indebtedness. The mortgage loan has a principal amount of $300.0 million, bears interest at a variable rate equal to SOFR plus 1.38% per annum and matures on July 19, 2025. The entire principal is subject to interest rate swap contracts through April 1, 2025 (See Note 8). The loan requires monthly interest-only payments during the term of the loan, with the entire principal due at maturity. The mortgage loan was recorded at fair value of approximately $295.5 million.

Unsecured Senior Notes

The following summarizes the unsecured senior notes outstanding as of December 31, 2023 (dollars in thousands):


	Coupon/Stated Rate		Effective Rate(1)		Principal Amount		Maturity Date(2)
10.5 Year Unsecured Senior Notes (3)	3.800	%	3.916	%	$	700,000	February 1, 2024
7 Year Unsecured Senior Notes	3.200	%	3.350	%	850,000		January 15, 2025
10 Year Unsecured Senior Notes	3.650	%	3.766	%	1,000,000		February 1, 2026
10 Year Unsecured Senior Notes	2.750	%	3.495	%	1,000,000		October 1, 2026
5 Year Unsecured Senior Notes	6.750	%	6.924	%	750,000		December 1, 2027
10 Year Unsecured Senior Notes	4.500	%	4.628	%	1,000,000		December 1, 2028
10 Year Unsecured Senior Notes	3.400	%	3.505	%	850,000		June 21, 2029
10.5 Year Unsecured Senior Notes	2.900	%	2.984	%	700,000		March 15, 2030
10.75 Year Unsecured Senior Notes	3.250	%	3.343	%	1,250,000		January 30, 2031
11 Year Unsecured Senior Notes	2.550	%	2.671	%	850,000		April 1, 2032
12 Year Unsecured Senior Notes	2.450	%	2.524	%	850,000		October 1, 2033
10.7 Year Unsecured Senior Notes	6.500	%	6.619	%	750,000		January 15, 2034
Total principal					10,550,000
Less:
Net unamortized discount					13,302
Deferred financing costs, net					45,081
Total					$	10,491,617

_______________

(1)Yield on issuance date including the effects of discounts on the notes, settlements of interest rate contracts and the amortization of financing costs.

(2)No principal amounts are due prior to maturity.

(3)See Note 17.

On May 15, 2023, BPLP completed a public offering of $750.0 million in aggregate principal amount of its 6.500% unsecured senior notes due 2034. The notes were priced at 99.697% of the principal amount to yield an effective rate (including financing fees) of approximately 6.619% per annum to maturity. The notes will mature on January 15, 2034, unless earlier redeemed. The aggregate net proceeds from the offering were approximately $741.3 million after deducting underwriting discounts and transaction expenses.

On September 1, 2023, BPLP completed the repayment of $500.0 million in aggregate principal amount of its 3.125% unsecured senior notes due September 1, 2023. The repayment price was approximately $507.8 million, which was equal to the stated principal plus approximately $7.8 million of accrued and unpaid interest to, but not including, the repayment date. Excluding the accrued and unpaid interest, the repayment price was equal to the principal amount being repaid.

The indenture relating to the unsecured senior notes contains certain financial restrictions and requirements, including (1) a leverage ratio not to exceed 60%, (2) a secured debt leverage ratio not to exceed 50%, (3) an interest coverage ratio of greater than 1.50, and (4) an unencumbered asset value of not less than 150% of unsecured debt. At December 31, 2023, BPLP was in compliance with each of these financial restrictions and requirements.

Unsecured Credit Facility

BPLP’s unsecured credit facility (the “2021 Credit Facility”) provides for borrowings of up to $1.815 billion, as described below in this Note 7, through BPLP’s revolving facility (the “Revolving Facility”), subject to customary conditions. The 2021 Credit Facility matures on June 15, 2026 and includes a sustainability-linked pricing component. Under the 2021 Credit Facility, BPLP may increase the total commitment by up to $500.0 million by increasing the amount of the Revolving Facility and/or by incurring one or more term loans, in each case, subject to syndication of the increase and other conditions (the “Accordion”). On September 28, 2023, BPLP exercised a portion of the Accordion with 3 new lenders to the 2021 Credit Facility (“New Lenders”). Each of the New Lenders

entered into a lender agreement with BPLP to provide an aggregate of $315.0 million in additional revolving credit commitments, which increased the maximum borrowing amount under the 2021 Credit Facility from $1.5 billion to $1.815 billion. All other terms of the 2021 Credit Facility remain unchanged.

At BPLP’s option, loans under the 2021 Credit Facility will bear interest at a rate per annum equal to (1) (a) in the case of loans denominated in Dollars, Term SOFR and SOFR, (b) in the case of loans denominated in Euro, EURIBOR, (c) in the case of loans denominated in Canadian Dollars, CDOR, and (d) in the case of loans denominated in Sterling, SONIA, in each case, plus a margin ranging from 70.0 to 140.0 basis points based on BPLP’s credit rating or (2) an alternate base rate equal to the greatest of (a) the Federal Funds rate plus 0.5%, (b) the administrative agent’s prime rate, (c) Term SOFR plus 1.00%, and (d) 1.00%, in each case, plus a margin ranging from 0 to 40 basis points based on BPLP’s credit rating.

The 2021 Credit Facility also features a sustainability-linked pricing component such that if BPLP meets certain sustainability performance targets, the applicable per annum interest rate will be reduced by one basis point. In addition, the 2021 Credit Facility contains a competitive bid option for up to 65% of the Revolving Facility that allows banks that are part of the lender consortium to bid to make loan advances to BPLP at a reduced interest rate.

Pursuant to the 2021 Credit Facility, BPLP is obligated to pay (1) in quarterly installments a facility fee on the total commitment under the Revolving Facility at a rate per annum ranging from 0.10% to 0.30% based on BPLP’s credit rating and (2) an annual fee on the undrawn amount of each letter of credit ranging from 0.70% to 1.40% based on BPLP’s credit rating.

On June 1, 2023, BPLP amended the 2021 Credit Facility to replace the LIBOR-based daily floating rate option with a SOFR-based daily floating rate option and to add options for SOFR-based term floating rates and rates for alternative currency loans. In addition, the amendment added a SOFR credit spread adjustment of 0.10%. Other than the foregoing, the material terms of the 2021 Credit Facility remain unchanged.

Based on BPLP’s December 31, 2023 credit rating, (1) the applicable Daily SOFR, Term SOFR, alternative currency daily rate, and alternative currency term rate margins are 0.775%, (2) the alternate base rate margin is zero basis points and (3) the facility fee is 0.15% per annum.

At December 31, 2023 and December 31, 2022, BPLP had no amount outstanding under the Revolving Facility.

Unsecured Term Loans

On May 17, 2022, BPLP entered into a credit agreement, which provided for a single borrowing of up to $730.0 million (the “2022 Unsecured Term Loan”). Upon entry into the credit agreement, BPLP exercised its option to draw $730.0 million under the 2022 Unsecured Term Loan, which was used for the acquisition of Madison Centre in Seattle, Washington. The 2022 Unsecured Term Loan was scheduled to mature on May 16, 2023 and bore interest at a variable rate equal to term SOFR plus 0.95% per annum based on BPLP’s credit rating at December 31, 2022.

On January 4, 2023, BPLP entered into a credit agreement that provided for a $1.2 billion unsecured term loan facility (the “2023 Unsecured Term Loan”). Under the credit agreement, BPLP may, at any time prior to the maturity date, increase total commitments by up to an additional $300.0 million in aggregate principal amount by increasing the existing 2023 Unsecured Term Loan or incurring one or more additional term loans, in each case, subject to syndication of the increase and other conditions. The 2023 Unsecured Term Loan matures on May 16, 2024, with one 12-month extension option, subject to customary conditions. Upon entry into the credit agreement, BPLP exercised its option to draw $1.2 billion under the 2023 Unsecured Term Loan, a portion of which was used to repay in full the $730.0 million outstanding under the 2022 Unsecured Term Loan. There was no prepayment penalty associated with the repayment of the 2022 Unsecured Term Loan.

At BPLP’s option, loans under the 2023 Unsecured Term Loan will bear interest at a rate per annum equal to (1) a base rate equal to the greatest of (a) the Federal Funds rate plus 0.5%, (b) the administrative agent’s prime rate, (c) Term SOFR for a one-month period plus 1.00%, and (d) 1.00%, in each case, plus a margin ranging from 0 to 60 basis points based on BPLP’s credit rating; or (2) a rate equal to adjusted Term SOFR with a one-month period plus a margin ranging from 75 to 160 basis points based on BPLP’s credit rating. Based on BPLP’s credit rating upon entry into the credit agreement, the base rate margin is 0 basis points and the Term SOFR margin is 0.85%. As of December 31, 2023, the 2023 Unsecured Term Loan bears interest at a rate equal to adjusted Term SOFR plus 0.85% (see Note 8).

At December 31, 2023, BPLP had $1.2 billion outstanding under the 2023 Unsecured Term Loan. At December 31, 2022, BPLP had $730.0 million outstanding under the 2022 Unsecured Term Loan.

2021 Credit Facility and 2023 Unsecured Term Loan Compliance

The agreements governing the 2021 Credit Facility and 2023 Unsecured Term Loan contain customary representations and warranties, affirmative and negative covenants and events of default provisions, including the failure to pay indebtedness, breaches of covenants and bankruptcy and other insolvency events, which could result in the acceleration of the obligation to repay, in the case of the 2021 Credit Facility, all outstanding amounts and the cancellation of all commitments outstanding under the 2021 Credit Facility and, in the case of the 2023 Unsecured Term Loan, any outstanding amount under the 2023 Unsecured Term Loan. Among other covenants, the 2021 Credit Facility and the 2023 Unsecured Term Loan require that BPLP maintain on an ongoing basis: (1) a leverage ratio not to exceed 60%, however, the leverage ratio may increase to no greater than 65% provided that it is reduced back to 60% within one year, (2) a secured debt leverage ratio not to exceed 55%, (3) a fixed charge coverage ratio of at least 1.40, (4) an unsecured debt leverage ratio not to exceed 60%, however, the unsecured debt leverage ratio may increase to no greater than 65% provided that it is reduced to 60% within one year, (5) an unsecured debt interest coverage ratio of at least 1.75 and (6) limitations on permitted investments. At December 31, 2023, BPLP was in compliance with each of these financial and other covenant requirements.

The entire disclosure for information about short-term and long-term debt arrangements, which includes amounts of borrowings under each line of credit, note payable, commercial paper issue, bonds indenture, debenture issue, own-share lending arrangements and any other contractual agreement to repay funds, and about the underlying arrangements, rationale for a classification as long-term, including repayment terms, interest rates, collateral provided, restrictions on use of assets and activities, whether or not in compliance with debt covenants, and other matters important to users of the financial statements, such as the effects of refinancing and noncompliance with debt covenants.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1B
-Subparagraph (h)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481139/470-20-50-1B

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 235
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08(c))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480678/235-10-S99-1

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 470
-Name Accounting Standards Codification
-Publisher FASB
-URI https://asc.fasb.org//470/tableOfContent

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1B
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481139/470-20-50-1B

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1B
-Subparagraph (g)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481139/470-20-50-1B

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
-SubTopic 20
-Name Accounting Standards Codification
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-Paragraph 1B
-Subparagraph (i)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481139/470-20-50-1B

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1C
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481139/470-20-50-1C

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1C
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-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481139/470-20-50-1C

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1C
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481139/470-20-50-1C

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1E
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481139/470-20-50-1E

Reference 11: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1I
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481139/470-20-50-1I

Reference 12: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
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-Name Accounting Standards Codification
-Section 50
-Paragraph 1I
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481139/470-20-50-1I

Reference 13: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1I
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481139/470-20-50-1I

Computation Of Basic And Diluted Earnings Per Share / Unit

Earnings Per Share / Common Unit (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Basic Earnings:
Net income attributable to the Company common shareholders / unitholders	$ 190,215	$ 848,947	$ 496,223
Net income (loss) attributable to the company's common shareholders / unitholders (in shares / units)	156,863,000	156,726,000	156,116,000
Net income (loss) attributable to the company's common shareholders / unitholders (in dollars per share / unit)	$ 1.21	$ 5.42	$ 3.18
Allocation of undistributed earnings to participating securities	$ 0	$ (891)	$ 0
Allocation of undistributed earnings to participating securities (in shares / units)	0	0	0
Allocation of undistributed earnings to participating securities (in dollars per share / unit)	$ 0	$ (0.01)	$ 0
Net Income Available To Common Stockholders After Allocation of Undistributed Earnings to Participating Securities Basic	$ 190,215	$ 848,056	$ 496,223
Weighted Average Number Of Shares Outstanding After Allocation of Undistributed Earnings to Participating Securities Basic (in shares)	156,863,000	156,726,000	156,116,000
Earnings Per Share After Allocation of Undistributed Earnings to Participating Securities Basic (dollars per share)	$ 1.21	$ 5.41	$ 3.18
Effect of Dilutive Securities:
Stock Based Compensation	$ 0	$ 0	$ 0
Stock Based Compensation (in shares / units)	338,000	411,000	260,000
Weighted Average Number Diluted Shares Outstanding Adjustment (per share)	$ 0	$ (0.01)	$ (0.01)
Diluted Earnings:
Diluted Earnings: Net income attributable to the Company's common shareholders / unitholders	$ 190,215	$ 848,056	$ 496,223
Diluted Earnings: Net income attributable to the Company's common shareholders / unitholders (in shares / units)	157,201,000	157,137,000	156,376,000
Diluted Earnings: Net income, Per Share Amount (in dollars per share / unit)	$ 1.21	$ 5.40	$ 3.17
Boston Properties Limited Partnership
Redeemable Common Units	17,933,000	17,634,000	17,034,000
Basic Earnings:
Net income attributable to the Company common shareholders / unitholders	$ 219,771	$ 957,265	$ 561,993
Net income (loss) attributable to the company's common shareholders / unitholders (in shares / units)	174,796,000	174,360,000	173,150,000
Net income (loss) attributable to the company's common shareholders / unitholders (in dollars per share / unit)	$ 1.26	$ 5.49	$ 3.25
Allocation of undistributed earnings to participating securities	$ 0	$ (991)	$ 0
Allocation of undistributed earnings to participating securities (in shares / units)	0	0	0
Allocation of undistributed earnings to participating securities (in dollars per share / unit)	$ 0	$ (0.01)	$ 0
Net Income Available To Common Stockholders After Allocation of Undistributed Earnings to Participating Securities Basic	$ 219,771	$ 956,274	$ 561,993
Weighted Average Number Of Shares Outstanding After Allocation of Undistributed Earnings to Participating Securities Basic (in shares)	174,796,000	174,360,000	173,150,000
Earnings Per Share After Allocation of Undistributed Earnings to Participating Securities Basic (dollars per share)	$ 1.26	$ 5.48	$ 3.25
Effect of Dilutive Securities:
Stock Based Compensation	$ 0	$ 0	$ 0
Stock Based Compensation (in shares / units)	338,000	411,000	260,000
Weighted Average Number Diluted Shares Outstanding Adjustment (per share)	$ (0.01)	$ (0.01)	$ (0.01)
Diluted Earnings:
Diluted Earnings: Net income attributable to the Company's common shareholders / unitholders	$ 219,771	$ 956,274	$ 561,993
Diluted Earnings: Net income attributable to the Company's common shareholders / unitholders (in shares / units)	175,134,000	174,771,000	173,410,000
Diluted Earnings: Net income, Per Share Amount (in dollars per share / unit)	$ 1.25	$ 5.47	$ 3.24

Earnings Per Share / Common Unit (Tables)

12 Months Ended

Dec. 31, 2023

Entity Information [Line Items]


	Year ended December 31, 2023
	Income (Numerator)		Shares (Denominator)	Per Share Amount
	(in thousands, except for per share amounts)
Basic Earnings:
Net income attributable to Boston Properties, Inc. common shareholders	$	190,215	156,863	$	1.21
Allocation of undistributed earnings to participating securities	—		—	—
Net income attributable to Boston Properties, Inc. common shareholders	190,215		156,863	1.21
Effect of Dilutive Securities:
Stock Based Compensation	—		338	—
Diluted Earnings:
Net income attributable to Boston Properties, Inc. common shareholders	$	190,215	157,201	$	1.21

	Year ended December 31, 2022
	Income (Numerator)		Shares (Denominator)	Per Share Amount
	(in thousands, except for per share amounts)
Basic Earnings:
Net income attributable to Boston Properties, Inc. common shareholders	$	848,947	156,726	$	5.42
Allocation of undistributed earnings to participating securities	(891)		—	(0.01)
Net income attributable to Boston Properties, Inc. common shareholders	848,056		156,726	5.41
Effect of Dilutive Securities:
Stock Based Compensation	—		411	(0.01)
Diluted Earnings:
Net income attributable to Boston Properties, Inc. common shareholders	$	848,056	157,137	$	5.40

	Year ended December 31, 2021
	Income (Numerator)		Shares (Denominator)	Per Share Amount
	(in thousands, except for per share amounts)
Basic Earnings:
Net income attributable to Boston Properties, Inc. common shareholders	$	496,223	156,116	$	3.18
Allocation of undistributed earnings to participating securities	—		—	—
Net income attributable to Boston Properties, Inc. common shareholders	496,223		156,116	3.18
Effect of Dilutive Securities:
Stock Based Compensation	—		260	(0.01)
Diluted Earnings:
Net income attributable to Boston Properties, Inc. common shareholders	$	496,223	156,376	$	3.17

Computation Of Basic And Diluted Earnings Per Share / Unit

Entity Information [Line Items]


	Year ended December 31, 2023
	Income (Numerator)		Units (Denominator)	Per Unit Amount
	(in thousands, except for per unit amounts)
Basic Earnings:
Net income attributable to Boston Properties Limited Partnership common unitholders	$	219,771	174,796	$	1.26
Allocation of undistributed earnings to participating securities	—		—	—
Net income attributable to Boston Properties Limited Partnership common unitholders	219,771		174,796	$	1.26
Effect of Dilutive Securities:
Stock Based Compensation	—		338	(0.01)
Diluted Earnings:
Net income attributable to Boston Properties Limited Partnership common unitholders	$	219,771	175,134	$	1.25

	Year ended December 31, 2022
	Income (Numerator)		Units (Denominator)	Per Unit Amount
	(in thousands, except for per unit amounts)
Basic Earnings:
Net income attributable to Boston Properties Limited Partnership common unitholders	$	957,265	174,360	$	5.49
Allocation of undistributed earnings to participating securities	(991)		—	(0.01)
Net income attributable to Boston Properties Limited Partnership common unitholders	956,274		174,360	5.48
Effect of Dilutive Securities:
Stock Based Compensation	—		411	(0.01)
Diluted Earnings:
Net income attributable to Boston Properties Limited Partnership common unitholders	$	956,274	174,771	$	5.47


	Year ended December 31, 2021
	Income (Numerator)		Units (Denominator)	Per Unit Amount
	(in thousands, except for per unit amounts)
Basic Earnings:
Net income attributable to Boston Properties Limited Partnership common unitholders	$	561,993	173,150	$	3.25
Allocation of undistributed earnings to participating securities	—		—	—
Net income attributable to Boston Properties Limited Partnership common unitholders	561,993		173,150	$	3.25
Effect of Dilutive Securities:
Stock Based Compensation	—		260	(0.01)
Diluted Earnings:
Net income attributable to Boston Properties Limited Partnership common unitholders	$	561,993	173,410	$	3.24

Consolidated Statements Of Comprehensive Income - USD ($)
$ in Thousands

12 Months Ended

Dec. 31, 2023

Dec. 31, 2022

Dec. 31, 2021

Net income (loss)

$ 291,424

$ 1,020,584

$ 631,932

Other comprehensive income :

Effective portion of interest rate contracts

(14,405)

19,396

8,544

Amortization of interest rate contracts

^[1]

6,703

6,707

6,704

Other comprehensive income (loss)

(7,702)

26,103

15,248

Comprehensive income

283,722

1,046,687

647,180

Net income attributable to noncontrolling interests

(101,209)

(171,637)

(126,737)

Other comprehensive (income) loss attributable to noncontrolling interests

274

(3,156)

(2,020)

Comprehensive income attributable to Boston Properties, Inc.

182,787

871,894

518,423

Effective portion of interest rate contracts

Net income (loss)

298,432

1,032,122

641,771

Other comprehensive income :

(14,405)

19,396

8,544

^[2]

Amortization of interest rate contracts

^[3]

6,703

6,707

6,704

Other comprehensive income (loss)

(7,702)

26,103

15,248

Comprehensive income

290,730

1,058,225

657,019

Net income attributable to noncontrolling interests

(79,237)

(75,433)

(71,382)

Comprehensive income attributable to Boston Properties, Inc.

$ 211,493

$ 982,792

$ 585,637

[1]	Amounts reclassified from comprehensive income primarily to interest expense within Boston Properties, Inc.’s Consolidated Statements of Operations
[2]	Includes the Company’s share of gain (loss) related to the effective portion of derivatives outstanding at its unconsolidated joint venture properties.
[3]	Amounts reclassified from comprehensive income primarily to interest expense within Boston Properties Limited Partnership’s Consolidated Statements of Operations.

Consolidated Statements Of Operations - USD ($)
shares in Thousands, $ in Thousands

12 Months Ended

Dec. 31, 2023

Dec. 31, 2022

Dec. 31, 2021

Revenue

Lease

$ 3,054,673

$ 2,918,368

$ 2,753,014

General and administrative

3,273,569

3,108,581

2,888,621

Expenses

Rental

1,183,947

1,108,070

1,021,151

170,158

146,378

151,573

4,313

2,905

5,036

830,813

749,775

717,336

2,239,227

2,050,056

1,920,581

Loss from unconsolidated joint ventures

(239,543)

(59,840)

(2,570)

Gains on sales of real estate

517

437,019

123,660

Interest and other income (loss)

10,058

69,964

11,940

5,704

Other Income - assignment fee

6,624

Gains (losses) from investments in securities

5,556

(6,453)

5,626

(79)

239

(150)

(45,182)

Net income attributable to noncontrolling interests

(579,572)

(437,139)

(423,346)

Net Income (loss)

291,424

1,020,584

631,932

Noncontrolling interests in property partnerships

(78,661)

(74,857)

(70,806)

Noncontrolling interest - common units of the Operating Partnership

(22,548)

(96,780)

(55,931)

Net income attributable to Boston Properties, Inc.

190,215

848,947

505,195

Preferred dividends / distributions

(2,560)

Preferred Stock Redemption Charge

(6,412)

Net income attributable to the Company common shareholders / unitholders

$ 190,215

$ 848,947

$ 496,223

Basic earnings per common share / unit attributable to the Company common shareholders / unitholders

Earnings Per Share After Allocation of Undistributed Earnings to Participating Securities Basic (dollars per share)

$ 1.21

$ 5.41

$ 3.18

Weighted average number of common shares / units outstanding (in shares / units)

156,863

156,726

156,116

Diluted earnings per common share / unit attributable to the Company common shareholders / unitholders

Diluted Earnings: Net income, Per Share Amount (in dollars per share / unit)

$ 1.21

$ 5.40

$ 3.17

Weighted average number of common and common equivalent shares / units outstanding (in shares / units)

157,201

157,137

156,376

Revenue

Lease

$ 3,054,673

$ 2,918,368

$ 2,753,014

General and administrative

3,273,569

3,108,581

2,888,621

Expenses

Rental

1,183,947

1,108,070

1,021,151

170,158

146,378

151,573

4,313

2,905

5,036

823,805

742,293

2,232,219

2,042,574

1,912,280

Loss from unconsolidated joint ventures

(239,543)

(59,840)

(2,570)

Gains on sales of real estate

517

441,075

125,198

Interest and other income (loss)

10,058

69,964

11,940

5,704

Other Income - assignment fee

6,624

Gains (losses) from investments in securities

5,556

(6,453)

5,626

(79)

239

(150)

(45,182)

Net income attributable to noncontrolling interests

(579,572)

(437,139)

(423,346)

Net Income (loss)

298,432

1,032,122

641,771

Noncontrolling interests in property partnerships

(78,661)

(74,857)

(70,806)

Net income attributable to Boston Properties, Inc.

219,771

957,265

570,965

Preferred dividends / distributions

(2,560)

Preferred Stock Redemption Charge

(6,412)

Net income attributable to the Company common shareholders / unitholders

$ 219,771

$ 957,265

$ 561,993

Basic earnings per common share / unit attributable to the Company common shareholders / unitholders

Earnings Per Share After Allocation of Undistributed Earnings to Participating Securities Basic (dollars per share)

$ 1.26

$ 5.48

$ 3.25

Weighted average number of common shares / units outstanding (in shares / units)

174,796

174,360

173,150

Diluted earnings per common share / unit attributable to the Company common shareholders / unitholders

Diluted Earnings: Net income, Per Share Amount (in dollars per share / unit)

$ 1.25

$ 5.47

$ 3.24

Weighted average number of common and common equivalent shares / units outstanding (in shares / units)

175,134

174,771

173,410

Parking and Other [Member]

Revenue

Parking and Other [Member] | Boston Properties Limited Partnership

$ 112,918

$ 107,225

$ 81,814

Revenue

112,918

107,225

81,814

Hotel [Member]

Revenue

^[1]

47,357

39,482

13,609

Expenses

Hotel [Member] | Boston Properties Limited Partnership

32,225

27,478

12,998

Revenue

47,357

39,482

13,609

Expenses

Management Service [Member]

32,225

27,478

12,998

Revenue

Management Service [Member] | Boston Properties Limited Partnership

40,850

28,056

27,697

Revenue

Real Estate, Other [Member]

40,850

28,056

27,697

Revenue

17,771

15,450

12,487

Expenses

Real Estate, Other [Member] | Boston Properties Limited Partnership

17,771

15,450

12,487

Revenue

17,771

15,450

12,487

Expenses

Real estate, at cost (amounts related to variable interest entities (“VIEs”) of $7,054,075 and $6,789,029 at December 31, 2023 and December 31, 2022, respectively)

$ 17,771

$ 15,450

$ 12,487

[1]	Rental Revenue is equal to Total Revenue per the Company’s Consolidated Statements of Operations, less Development and Management Services Revenue and Direct Reimbursements of Payroll and Related Costs from Management Services Contracts Revenue per the Consolidated Statements of Operations.

Real Estate Weighted-Average Useful Life of Intangible Assets by Major Class (Details) - Santa Monica Business Park [Member]	Dec. 14, 2023
In-Place Lease Intangibles
Real Estate Properties [Line Items]
Acquired Finite-Lived Intangible Assets, Weighted Average Useful Life	2 years 10 months 24 days
Ground Lease
Real Estate Properties [Line Items]
Acquired Finite-Lived Intangible Assets, Weighted Average Useful Life	4 years 2 months 12 days
Above Market Lease Intangibles [Member]
Real Estate Properties [Line Items]
Acquired Finite-Lived Intangible Assets, Weighted Average Useful Life	2 years 3 months 18 days
Below Market Lease [Member]
Real Estate Properties [Line Items]
Acquired Finite-Lived Intangible Assets, Weighted Average Useful Life	5 years 1 month 6 days

Consolidated Balance Sheets - USD ($)
$ in Thousands

Dec. 31, 2023

Dec. 31, 2022

ASSETS

$ 26,749,209

$ 25,389,663

Right of use assets - finance leases (amounts related to VIEs of $21,000 and $21,000 at December 31, 2023 and December 31, 2022, respectively)

401,680

237,510

Right of use assets - operating leases (amounts related to VIEs of $158,885 and $0 at December 31, 2023 and December 31, 2022, respectively)

^[1]

324,298

167,351

Less: accumulated depreciation (amounts related to VIEs of $(1,501,483) and $(1,381,401) at December 31, 2023 and December 31, 2022, respectively)

(6,881,728)

(6,298,082)

Cash and cash equivalents (amounts related to VIEs of $245,317 and $259,658 at December 31, 2023 and December 31, 2022, respectively)

20,593,459

19,496,442

1,531,477

690,333

Cash held in escrows (amounts related to VIEs of $22,160 and $0 at December 31, 2023 and December 31, 2022, respectively)

81,090

46,479

Investments in securities

36,337

32,277

Tenant and other receivables, net (amounts related to VIEs of $27,987 and $16,521 at December 31, 2023 and December 31, 2022, respectively)

122,407

81,389

1,714

Accrued rental income, net (amounts related to VIEs of $401,159 and $367,138 at December 31, 2023 and December 31, 2022, respectively)

13,704

12,811

1,355,212

1,276,580

Deferred charges, net (amounts related to VIEs of $175,383 and $176,597 at December 31, 2023 and December 31, 2022, respectively)

760,421

733,282

Prepaid expenses and other assets (amounts related to VIEs of $11,824 and $11,647 at December 31, 2023 and December 31, 2022, respectively)

64,230

43,589

1,377,319

1,715,911

26,026,149

24,207,669

Mortgage notes payable, net (amounts related to VIEs of $3,277,185 and $3,272,368 at December 31, 2023 and December 31, 2022, respectively)

4,166,379

3,272,368

10,491,617

10,237,968

Lease liabilities - finance leases (amounts related to VIEs of $20,794 and $20,604 at December 31, 2023 and December 31, 2022, respectively)

1,198,301

730,000

417,961

249,335

Lease liabilities - operating leases (amounts related to VIEs of $145,826 and $0 at December 31, 2023 and December 31, 2022, respectively)

350,391

204,686

Accounts payable and accrued expenses (amounts related to VIEs of $59,667 and $29,466 at December 31, 2023 and December 31, 2022, respectively)

458,329

417,545

Dividends and distributions payable

171,176

170,643

Accrued interest payable

133,684

103,774

Other liabilities (amounts related to VIEs of $115,275 and $114,232 at December 31, 2023 and December 31, 2022, respectively)

445,947

450,918

Total liabilities

17,833,785

15,837,237

Redeemable deferred stock units— 119,471 and 97,853 units outstanding at redemption value at December 31, 2023 and December 31, 2022, respectively

$ 8,383

$ 6,613

Excess stock, shares outstanding

Excess stock, shares issued

Preferred stock / units, shares / units issued (in shares / units)

Preferred stock / units, shares / units outstanding (in shares / units)

Equity / Capital:

Excess stock, $0.01 par value, 150,000,000 shares authorized, none issued or outstanding

$ 0

Preferred stock, $0.01 par value, 50,000,000 shares authorized, none issued or outstanding

Common stock, $0.01 par value, 250,000,000 shares authorized, 157,019,766 and 156,836,767 issued and 156,940,866 and 156,757,867 outstanding at December 31, 2023 and December 31, 2022, respectively

1,569

1,568

Additional paid-in capital

6,715,149

6,539,147

Dividends in excess of earnings

$ (816,152)

$ (391,356)

Treasury common stock at cost, shares

78,900

Treasury common stock at cost, 78,900 shares at December 31, 2023 and December 31, 2022

$ (2,722)

Accumulated other comprehensive loss

(21,147)

(13,718)

Total stockholders' equity attributable to Boston Properties, Inc.

5,876,697

6,132,919

Noncontrolling interests:

Common units of the Operating Partnership

666,580

683,583

Property partnerships

1,640,704

1,547,317

Total equity / capital

8,183,981

8,363,819

26,026,149

24,207,669

Related Party

ASSETS

Variable Interest Entity, Primary Beneficiary [Member]

88,779

78,576

ASSETS

Real estate, at cost (amounts related to variable interest entities (“VIEs”) of $7,054,075 and $6,789,029 at December 31, 2023 and December 31, 2022, respectively)

7,054,075

6,789,029

Right of use assets - finance leases (amounts related to VIEs of $21,000 and $21,000 at December 31, 2023 and December 31, 2022, respectively)

21,000

Right of use assets - operating leases (amounts related to VIEs of $158,885 and $0 at December 31, 2023 and December 31, 2022, respectively)

158,885

Less: accumulated depreciation (amounts related to VIEs of $(1,501,483) and $(1,381,401) at December 31, 2023 and December 31, 2022, respectively)

(1,501,483)

(1,381,401)

Cash and cash equivalents (amounts related to VIEs of $245,317 and $259,658 at December 31, 2023 and December 31, 2022, respectively)

245,317

259,658

Cash held in escrows (amounts related to VIEs of $22,160 and $0 at December 31, 2023 and December 31, 2022, respectively)

22,160

Tenant and other receivables, net (amounts related to VIEs of $27,987 and $16,521 at December 31, 2023 and December 31, 2022, respectively)

27,987

16,521

Accrued rental income, net (amounts related to VIEs of $401,159 and $367,138 at December 31, 2023 and December 31, 2022, respectively)

401,159

367,138

Deferred charges, net (amounts related to VIEs of $175,383 and $176,597 at December 31, 2023 and December 31, 2022, respectively)

175,383

176,597

Prepaid expenses and other assets (amounts related to VIEs of $11,824 and $11,647 at December 31, 2023 and December 31, 2022, respectively)

11,824

11,647

Mortgage notes payable, net (amounts related to VIEs of $3,277,185 and $3,272,368 at December 31, 2023 and December 31, 2022, respectively)

3,277,185

3,272,368

Lease liabilities - finance leases (amounts related to VIEs of $20,794 and $20,604 at December 31, 2023 and December 31, 2022, respectively)

20,794

20,604

Lease liabilities - operating leases (amounts related to VIEs of $145,826 and $0 at December 31, 2023 and December 31, 2022, respectively)

145,826

Accounts payable and accrued expenses (amounts related to VIEs of $59,667 and $29,466 at December 31, 2023 and December 31, 2022, respectively)

59,667

29,466

Other liabilities (amounts related to VIEs of $115,275 and $114,232 at December 31, 2023 and December 31, 2022, respectively)

115,275

114,232

Real estate, at cost (amounts related to variable interest entities (“VIEs”) of $7,054,075 and $6,789,029 at December 31, 2023 and December 31, 2022, respectively)

ASSETS

26,382,944

25,022,149

Right of use assets - finance leases (amounts related to VIEs of $21,000 and $21,000 at December 31, 2023 and December 31, 2022, respectively)

401,680

237,510

Right of use assets - operating leases (amounts related to VIEs of $158,885 and $0 at December 31, 2023 and December 31, 2022, respectively)

^[1]

324,298

167,351

Less: accumulated depreciation (amounts related to VIEs of $(1,501,483) and $(1,381,401) at December 31, 2023 and December 31, 2022, respectively)

(6,758,361)

(6,180,474)

Cash and cash equivalents (amounts related to VIEs of $245,317 and $259,658 at December 31, 2023 and December 31, 2022, respectively)

20,350,561

19,246,536

1,531,477

690,333

Cash held in escrows (amounts related to VIEs of $22,160 and $0 at December 31, 2023 and December 31, 2022, respectively)

81,090

46,479

Investments in securities

36,337

32,277

Tenant and other receivables, net (amounts related to VIEs of $27,987 and $16,521 at December 31, 2023 and December 31, 2022, respectively)

122,407

81,389

1,714

Accrued rental income, net (amounts related to VIEs of $401,159 and $367,138 at December 31, 2023 and December 31, 2022, respectively)

13,704

12,811

1,355,212

1,276,580

Deferred charges, net (amounts related to VIEs of $175,383 and $176,597 at December 31, 2023 and December 31, 2022, respectively)

760,421

733,282

Prepaid expenses and other assets (amounts related to VIEs of $11,824 and $11,647 at December 31, 2023 and December 31, 2022, respectively)

64,230

43,589

1,377,319

1,715,911

25,783,251

23,957,763

Mortgage notes payable, net (amounts related to VIEs of $3,277,185 and $3,272,368 at December 31, 2023 and December 31, 2022, respectively)

4,166,379

3,272,368

10,491,617

10,237,968

Lease liabilities - finance leases (amounts related to VIEs of $20,794 and $20,604 at December 31, 2023 and December 31, 2022, respectively)

1,198,301

730,000

417,961

249,335

Lease liabilities - operating leases (amounts related to VIEs of $145,826 and $0 at December 31, 2023 and December 31, 2022, respectively)

350,391

204,686

Accounts payable and accrued expenses (amounts related to VIEs of $59,667 and $29,466 at December 31, 2023 and December 31, 2022, respectively)

458,329

417,545

Dividends and distributions payable

171,176

170,643

Accrued interest payable

133,684

103,774

Other liabilities (amounts related to VIEs of $115,275 and $114,232 at December 31, 2023 and December 31, 2022, respectively)

445,947

450,918

Total liabilities

17,833,785

15,837,237

Redeemable deferred stock units— 119,471 and 97,853 units outstanding at redemption value at December 31, 2023 and December 31, 2022, respectively

8,383

6,613

Noncontrolling interest:

Redeemable partnership units— 16,508,277 and 16,531,172 common units and 2,065,861 and 1,679,175 long term incentive units outstanding at redemption value at December 31, 2023 and December 31, 2022, respectively

1,347,575

1,280,886

Equity / Capital:

Boston Properties Limited Partnership partners’ capital— 1,755,150 and 1,749,682 general partner units and 155,185,716 and 155,008,185 limited partner units outstanding at December 31, 2023 and December 31, 2022, respectively

4,973,951

5,299,428

Accumulated other comprehensive loss

(21,147)

(13,718)

Total partners’ capital

4,952,804

5,285,710

Noncontrolling interests in property partnerships

1,640,704

1,547,317

Noncontrolling interests:

Total equity / capital

6,593,508

6,833,027

Boston Properties Limited Partnership | Related Party

25,783,251

23,957,763

ASSETS

Boston Properties Limited Partnership | Variable Interest Entity, Primary Beneficiary [Member]

88,779

78,576

ASSETS

Real estate, at cost (amounts related to variable interest entities (“VIEs”) of $7,054,075 and $6,789,029 at December 31, 2023 and December 31, 2022, respectively)

7,054,075

6,789,029

Right of use assets - finance leases (amounts related to VIEs of $21,000 and $21,000 at December 31, 2023 and December 31, 2022, respectively)

21,000

Right of use assets - operating leases (amounts related to VIEs of $158,885 and $0 at December 31, 2023 and December 31, 2022, respectively)

158,885

Less: accumulated depreciation (amounts related to VIEs of $(1,501,483) and $(1,381,401) at December 31, 2023 and December 31, 2022, respectively)

(1,501,483)

(1,381,401)

Cash and cash equivalents (amounts related to VIEs of $245,317 and $259,658 at December 31, 2023 and December 31, 2022, respectively)

245,317

259,658

Cash held in escrows (amounts related to VIEs of $22,160 and $0 at December 31, 2023 and December 31, 2022, respectively)

22,160

Tenant and other receivables, net (amounts related to VIEs of $27,987 and $16,521 at December 31, 2023 and December 31, 2022, respectively)

27,987

16,521

Accrued rental income, net (amounts related to VIEs of $401,159 and $367,138 at December 31, 2023 and December 31, 2022, respectively)

401,159

367,138

Deferred charges, net (amounts related to VIEs of $175,383 and $176,597 at December 31, 2023 and December 31, 2022, respectively)

175,383

176,597

Prepaid expenses and other assets (amounts related to VIEs of $11,824 and $11,647 at December 31, 2023 and December 31, 2022, respectively)

11,824

11,647

Mortgage notes payable, net (amounts related to VIEs of $3,277,185 and $3,272,368 at December 31, 2023 and December 31, 2022, respectively)

3,277,185

3,272,368

Lease liabilities - finance leases (amounts related to VIEs of $20,794 and $20,604 at December 31, 2023 and December 31, 2022, respectively)

20,794

20,604

Lease liabilities - operating leases (amounts related to VIEs of $145,826 and $0 at December 31, 2023 and December 31, 2022, respectively)

145,826

Accounts payable and accrued expenses (amounts related to VIEs of $59,667 and $29,466 at December 31, 2023 and December 31, 2022, respectively)

59,667

29,466

Other liabilities (amounts related to VIEs of $115,275 and $114,232 at December 31, 2023 and December 31, 2022, respectively)

$ 115,275

$ 114,232

[1]	See Note 4.

Leases

12 Months Ended

Dec. 31, 2023

Leases [Abstract]

Leases of Lessor Disclosure [Text Block]

4. Leases

The Company estimates the collectability of its accrued rent and accounts receivable balances related to lease revenue. When evaluating the collectability of these accrued rent and accounts receivable balances, management considers tenant creditworthiness, current economic trends and changes in tenants’ payment patterns, on a lease-by-lease basis. If the Company determines that the accrued rent and/or accounts receivable balances are no longer probable of collection then the balances are written-off and the lease is recognized on a cash basis.

If applicable, information related to write-offs of accrued rent, net balances and accounts receivable, net

balances and reinstatements of accrued rent balances for the Company’s unconsolidated joint ventures can be

found in Note 6.

Lessor

Operating Leases

The following table summarizes the components of lease revenue recognized during the years ended December 31, 2023, 2022 and 2021 included within the Company's Consolidated Statements of Operations (in thousands):


	Year ended December 31,
Lease Revenue	2023		2022		2021
Fixed contractual payments	$	2,503,106	$	2,426,007	$	2,319,362
Variable lease payments	550,641		492,361		433,652
Sales-type lease	926		—		—
	$	3,054,673	$	2,918,368	$	2,753,014

The future contractual lease payments to be received (excluding operating expense reimbursements and percentage rent) by the Company as of December 31, 2023, under non-cancelable operating leases which expire on various dates through 2049 (in thousands):


Years Ending December 31,
2024	$	2,420,047
2025	2,444,826
2026	2,379,371
2027	2,281,437
2028	2,140,919
Thereafter	15,592,965

No single tenant represented more than 10.0% of the Company’s total lease revenue for the years ended December 31, 2023, 2022 and 2021.

On November 6, 2023, WeWork Inc. and certain of its direct and indirect subsidiaries (collectively, “WeWork”) filed voluntary petitions to commence proceedings under Chapter 11 of title 11 of the United States Code in the United States Bankruptcy Court for the District of New Jersey. At December 31, 2023, WeWork is a tenant at four of the Company’s premier workplaces and leases an aggregate of approximately 367,338 square feet, representing approximately 0.87% of the Company’s share of its in-service portfolio square footage. There can be no assurance that WeWork will not reject one or more of the four leases.

Sales-type Lease

For the years ended December 31, 2023 and 2022, the Company had one non-cancelable ground lease obligation, as lessor, that is classified as a sales-type lease with an expiration date through 2119. Upon commencement of this lease, the Company recognized a gain on sale of approximately $10.1 million associated with the derecognition of the asset. The Company recognized approximately $0.9 million of interest income that is recorded in lease revenue on its Consolidated Statement of Operations for the year ended December 31, 2023. The Company did not recognize any interest income during the year ended December 31, 2022.

The following table provides the future contractual payments to be received as of December 31, 2023 (in thousands):


	December 31, 2023
2024	$	31
2025	124
2026	372
2027	756
2028	775
Thereafter	267,474
Total lease payments to be received	269,532
Less:
Interest portion	255,579
Sales-type lease receivable	13,953
Unguaranteed residual asset	18
Current expected credit loss adjustment	(267)
Sales-type lease receivable, net	$	13,704

The following table provides the future contractual payments to be received as of December 31, 2022 (in thousands):


	December 31, 2022
2023	$	—
2024	31
2025	124
2026	372
2027	756
Thereafter	268,249
Total lease payments to be received	269,532
Less:
Interest portion	256,504
Sales-type lease receivable	13,028
Unguaranteed residual asset	17
Current expected credit loss adjustment	(234)
Sales-type lease receivable, net	$	12,811

Lessee, Operating Leases

Lessee

For the year ended December 31, 2023, the Company had one cancelable and four non-cancelable ground lease obligations, as lessee, which were classified as operating leases, with various initial term expiration dates through 2125. For the years ended December 31, 2022 and 2021, the Company had four non-cancelable ground lease obligations, as lessee, which were classified as operating leases, with various initial term expiration dates through 2114. The Company recognizes ground rent expense on a straight-line basis over the terms of the respective ground lease agreements. As of December 31, 2023, the amounts disclosed below include a ground lease that is subject to variable payments and extension options. At December 31, 2022 and December 31, 2021, no ground leases were subject to variable payments and extension options. As of December 31, 2023, December 31, 2022 and December 31, 2021, none of the amounts disclosed below contains residual value guarantees.

For the year ended December 31, 2023, the Company had five finance lease obligations with various initial term expiration dates through 2094. For the years ended December 31, 2022 and 2021, the Company had four finance lease obligations with various initial term expiration dates through 2094.

The following table provides lease cost information for the Company’s operating and finance leases for the years ended December 31, 2023, 2022 and 2021 (in thousands):


	Year ended December 31,
Lease costs	2023		2022		2021
Operating lease costs (1)	$	14,451	$	12,700	$	13,151
Finance lease costs
Amortization of right of use asset (2)	$	2,821	$	697	$	547
Interest on lease liabilities (3)	$	13,747	$	3,236	$	2,471

_______________

(1)One of the operating leases relate to assets under development for a portion of the year ended December 31, 2023 and as such, the operating lease costs were capitalized. For December 31, 2022 and 2021, no operating leases related to assets under development.

(2)The finance leases relate to either land, buildings or assets that remain in development. For land leases classified as finance leases because of a purchase option that the Company views as an economic incentive, the Company follows its existing policy and does not depreciate land because it is assumed to have an indefinite life. For all other finance leases, the Company would amortize the right of use asset over the shorter of the useful life of the asset or the lease term. If the finance lease relates to a property under development, the amortization of the right of use asset may be eligible for capitalization. For assets under development, depreciation may commence once the asset is placed in-service and depreciation would be recognized in accordance with the Company’s policy.

(3)One, one and two of the finance leases relate to assets under development for all or a portion of the years ended December 31, 2023, December 31, 2022 and December 31, 2021, respectively, and as such, a portion of the interest amount was capitalized.

The following table provides other quantitative information for the Company’s operating and finance leases as of December 31, 2023 and December 31, 2022:


	December 31, 2023		December 31, 2022
Other information
Weighted-average remaining lease term (in years)
Operating leases	70		49
Finance leases	60		68
Weighted-average discount rate
Operating leases	6.6	%	5.7	%
Finance leases	6.1	%	6.2	%

The following table provides a maturity analysis for the Company’s lease liabilities related to its operating and finance leases as of December 31, 2023 (in thousands):


	Operating		Finance
2024 (1)	$	29,989	$	70,370
2025	35,733		32,232
2026	10,100		31,972
2027	9,885		32,170
2028 (1)	14,637		118,232
Thereafter	3,546,537		1,342,174
Total lease payments	3,646,881		1,627,150
Less:
Interest portion	3,296,490		1,209,189
Present value of lease payments	$	350,391	$	417,961

_______________

(1)Finance lease payments in 2024 and 2028 include approximately $38.7 million and $105.3 million, respectively, related to purchase options that the Company was reasonably certain it would exercise upon execution of the ground leases. There can be no assurance that the Company will ultimately exercise the purchase options on the schedule currently contemplated or at all.

The following table provides a maturity analysis for the Company’s lease liabilities related to its operating and finance leases as of December 31, 2022 (in thousands):


	Operating		Finance
2023	$	22,415	$	9,306
2024 (1)	22,274		49,343
2025	10,308		9,971
2026	10,100		10,166
2027	9,885		10,364
Thereafter	528,915		1,352,647
Total lease payments	603,897		1,441,797
Less:
Interest portion	399,211		1,192,462
Present value of lease payments	$	204,686	$	249,335

_______________

(1)Finance lease payments in 2024 include approximately $38.7 million related to a purchase option that the Company was reasonably certain it would exercise upon execution of the ground lease. There can be no assurance that the Company will ultimately exercise the purchase options on the schedule currently contemplated.

On August 1, 2023, a consolidated joint venture in which the Company has a 55% interest executed an up to 99-year ground lease with the Metropolitan Transportation Authority for an approximately 25,000 square foot site, the 343 Madison Avenue project in New York City (see Note 10). The 343 Madison Avenue project contemplates the construction of (1) a direct entrance to the Long Island Railroad’s new east side access project (Grand Central Madison) (“Phase 1”) and (2) an approximately 900,000 square foot premier workplace building with ground floor retail (“Phase 2”). The joint venture has the option until July 31, 2025 to terminate the ground lease prior to construction of the new building and receive reimbursement of up to $117.0 million for the cost of the construction of Phase 1. The Company is reasonably certain that it will not exercise this termination option as the Company completed a long-term competitive process to obtain the right to ground lease this site. There can be no assurance that Phase 1 will be completed on the terms currently contemplated or that Phase 2 of the development project will commence on the terms currently contemplated or at all.

There is no rent due under the ground lease for the period from August 1, 2023 through July 31, 2028, with the exception of a payment of approximately $21.8 million that is due on July 31, 2025. Beginning August 1, 2028, the lease requires rent of approximately $10.9 million per year with adjustments every five years, with a minimum increase of 110% of the ground rent from the prior year. The incremental borrowing rate for this lease is 8.14% per annum. The net present value of the ground lease payments is approximately $141.1 million. The lease required the joint venture to pay a non-refundable deposit totaling $25.0 million, of which $15.0 million was placed in escrow in 2022 with the signing of a pre-lease agreement and $10.0 million was paid in 2023 as a requirement of entering into the ground lease. The consolidated joint venture classifies this ground lease as an operating lease. As a result, the consolidated joint venture recorded a Right of Use Assets – Operating Leases and Lease Liabilities – Operating Leases of approximately $166.8 million and $141.1 million, respectively, on its Consolidated Balance Sheets as of December 31, 2023. The 343 Madison Avenue ground lease had operating lease costs of approximately $12.6 million, that was all capitalized, for the year ended December 31, 2023.

On December 14, 2023, the Company completed the acquisition of its joint venture partner’s 45% interest in the joint venture entity that owns Santa Monica Business Park located in Santa Monica, California (See Note 3). Approximately 70% of Santa Monica Business Park’s rentable square footage is subject to a ground lease. The ground lease has an expiration date of February 4, 2054 with the option to renew the term for four additional periods of 11 years each, subject to certain conditions. The ground lease requires monthly rental payments with increases every five years, starting in 2028. The ground lease provides the right to purchase the land underlying the properties in 2028 with subsequent purchase rights every 15 years. The option to purchase the land is considered a bargain purchase option and as a result, the ground lease is accounted for as a finance lease. The Company’s incremental borrowing rate for this ground lease is 5.79% per annum. The net present value of the total ground lease payments is approximately $163.1 million. The Company recorded a Right of Use Assets – Finance lease and Lease liabilities – Finance Lease of approximately $164.1 million and $163.1 million, respectively, on its Consolidated Balance Sheets for the year ended December 31, 2023. In accordance with Accounting Standards Codification 805 “Business Combinations” the Company was required to fair value the ground lease. The ground lease was determined to be above fair value and as a result the Company recognized approximately $46.7 million

within Other Liabilities on its Consolidated Balance Sheets for the year ended December 31, 2023. The Santa Monica Business Park ground lease had interest expense of approximately $0.4 million for the year ended December 31, 2023.

Lessor, Operating Leases [Text Block]

Lessor

Operating Leases


	Year ended December 31,
Lease Revenue	2023		2022		2021
Fixed contractual payments	$	2,503,106	$	2,426,007	$	2,319,362
Variable lease payments	550,641		492,361		433,652
Sales-type lease	926		—		—
	$	3,054,673	$	2,918,368	$	2,753,014


Years Ending December 31,
2024	$	2,420,047
2025	2,444,826
2026	2,379,371
2027	2,281,437
2028	2,140,919
Thereafter	15,592,965

No single tenant represented more than 10.0% of the Company’s total lease revenue for the years ended December 31, 2023, 2022 and 2021.

Lessor, Sales-type Leases

Sales-type Lease

The following table provides the future contractual payments to be received as of December 31, 2023 (in thousands):


	December 31, 2023
2024	$	31
2025	124
2026	372
2027	756
2028	775
Thereafter	267,474
Total lease payments to be received	269,532
Less:
Interest portion	255,579
Sales-type lease receivable	13,953
Unguaranteed residual asset	18
Current expected credit loss adjustment	(267)
Sales-type lease receivable, net	$	13,704

The following table provides the future contractual payments to be received as of December 31, 2022 (in thousands):


	December 31, 2022
2023	$	—
2024	31
2025	124
2026	372
2027	756
Thereafter	268,249
Total lease payments to be received	269,532
Less:
Interest portion	256,504
Sales-type lease receivable	13,028
Unguaranteed residual asset	17
Current expected credit loss adjustment	(234)
Sales-type lease receivable, net	$	12,811

Segment Information

12 Months Ended

Dec. 31, 2023

Segment Reporting [Abstract]

Segment Reporting Disclosure [Text Block]

12. Segment Information

The following tables present reconciliations of Net Income Attributable to Boston Properties, Inc. common shareholders to the Company’s share of Net Operating Income and Net Income Attributable to Boston Properties Limited Partnership common unitholders to the Company’s share of Net Operating Income for the years ended December 31, 2023, 2022 and 2021.

BXP


	Year ended December 31,
		2023		2022		2021
		(in thousands)
Net income attributable to Boston Properties, Inc. common shareholders		$	190,215	$	848,947	$	496,223
Add:
Preferred stock redemption charge		—		—		6,412
Preferred dividends		—		—		2,560
Noncontrolling interest—common units of the Operating Partnership		22,548		96,780		55,931
Noncontrolling interests in property partnerships		78,661		74,857		70,806
Interest expense		579,572		437,139		423,346
Losses from early extinguishment of debt		—		—		45,182
Losses from interest rate contracts		79		—		—
Net operating income from unconsolidated joint ventures		160,695		146,081		107,756
Loss from unconsolidated joint ventures		239,543		59,840		2,570
Depreciation and amortization expense		830,813		749,775		717,336
Transaction costs		4,313		2,905		5,036
Payroll and related costs from management services contracts		17,771		15,450		12,487
General and administrative expense		170,158		146,378		151,573
Less:
Net operating income attributable to noncontrolling interests in property partnerships		194,365		191,812		186,304
Unrealized gain (loss) on non-real estate investment		239		(150)		—
Gains (losses) from investments in securities		5,556		(6,453)		5,626
Other income - assignment fee		—		6,624		—
Interest and other income (loss)		69,964		11,940		5,704
Gain on sales-type lease		—		10,058		—
Gains on sales of real estate		517		437,019		123,660
Direct reimbursements of payroll and related costs from management services contracts		17,771		15,450		12,487
Development and management services revenue		40,850		28,056		27,697
Company’s share of Net Operating Income		$	1,965,106	$	1,883,796	$	1,735,740

BPLP


	Year ended December 31,
		2023		2022		2021
		(in thousands)
Net income attributable to Boston Properties Limited Partnership common unitholders		$	219,771	$	957,265	$	561,993
Add:
Preferred unit redemption charge		—		—		6,412
Preferred distributions		—		—		2,560
Noncontrolling interests in property partnerships		78,661		74,857		70,806
Interest expense		579,572		437,139		423,346
Losses from early extinguishment of debt		—		—		45,182
Losses from interest rate contracts		79		—		—
Net operating income from unconsolidated joint ventures		160,695		146,081		107,756
Loss from unconsolidated joint ventures		239,543		59,840		2,570
Depreciation and amortization expense		823,805		742,293		709,035
Transaction costs		4,313		2,905		5,036
Payroll and related costs from management services contracts		17,771		15,450		12,487
General and administrative expense		170,158		146,378		151,573
Less:
Net operating income attributable to noncontrolling interests in property partnerships		194,365		191,812		186,304
Unrealized gain (loss) on non-real estate investment		239		(150)		—
Gains (losses) from investments in securities		5,556		(6,453)		5,626
Other income - assignment fee		—		6,624		—
Interest and other income (loss)		69,964		11,940		5,704
Gain on sales-type lease		—		10,058		—
Gains on sales of real estate		517		441,075		125,198
Direct reimbursements of payroll and related costs from management services contracts		17,771		15,450		12,487
Development and management services revenue		40,850		28,056		27,697
Company’s share of Net Operating Income		$	1,965,106	$	1,883,796	$	1,735,740

Net operating income (“NOI”) is a non-GAAP financial measure equal to net income attributable to Boston Properties, Inc. common shareholders and net income attributable to Boston Properties Limited Partnership common unitholders, as applicable, the most directly comparable GAAP financial measures, plus (1) preferred stock/unit redemption charge, preferred dividends/distributions, net income attributable to noncontrolling interests, interest expense, losses from early extinguishment of debt, losses from interest rate contracts, loss from unconsolidated joint ventures, depreciation and amortization expense, transaction costs, payroll and related costs from management services contracts and corporate general and administrative expense less (2) unrealized gain (loss) on non-real estate investment, gains (losses) from investments in securities, other income - assignment fee, interest and other income (loss), gain on sales-type lease, gains on sales of real estate, direct reimbursements of payroll and related costs from management services contracts and development and management services revenue. The Company believes NOI is useful to investors as a performance measure and believes it provides useful information to investors regarding its results of operations and financial condition because, when compared across periods, it reflects the impact on operations from trends in occupancy rates, rental rates, operating costs and acquisition and development activity on an unleveraged basis, providing perspective not immediately apparent from net income attributable to Boston Properties, Inc. common shareholders and net income attributable to Boston Properties Limited Partnership common unitholders. For example, interest expense is not necessarily linked to the operating performance of a real estate asset and is often incurred at the corporate level as opposed to the property

level. Similarly, interest expense may be incurred at the property level even though the financing proceeds may be used at the corporate level (e.g., used for other investment activity). In addition, depreciation and amortization expense, because of historical cost accounting and useful life estimates, may distort operating performance measures at the property level. NOI presented by the Company may not be comparable to NOI reported by other REITs or real estate companies that define NOI differently.

The Company’s internal reporting utilizes its share of NOI, which includes its share of NOI from consolidated and unconsolidated joint ventures, which is a non-GAAP financial measure that is calculated as the consolidated amount, plus the Company’s share of the amount from the Company’s unconsolidated joint ventures (calculated based upon the Company’s economic percentage ownership interest and, in some cases, after priority allocations), less the Company’s partners’ share of the amount from the Company’s consolidated joint ventures (calculated based upon the partners’ economic percentage ownership interests and, in some cases, after priority allocations, income allocation to private REIT shareholders and their share of fees due to the Company). The Company’s share of NOI from unconsolidated joint ventures, as defined above, also does not include its share of unrealized gain (loss) on derivative instruments, gain on sale of investment, gain on investment, gain (loss) on sale/consolidation and impairment losses on investments, all of which are included within Loss from Unconsolidated Joint Ventures in the Company’s Consolidated Statements of Operations. Management utilizes its share of NOI in assessing its performance as the Company has several significant joint ventures and, in some cases, the Company exercises significant influence over, but does not control, the joint venture, in which case GAAP requires that the Company account for the joint venture entity using the equity method of accounting and the Company does not consolidate it for financial reporting purposes. In other cases, GAAP requires that the Company consolidate the venture even though the Company’s partner(s) owns a significant percentage interest. As a result, the presentations of the Company’s share of NOI should not be considered a substitute for, and should only be considered together with and as a supplement to, the Company’s financial information presented in accordance with GAAP.

Asset information by segment is not reported because the Company does not use this measure to assess performance. Therefore, depreciation and amortization expense is not allocated among segments. Interest expense, losses from early extinguishment of debt, losses from interest rate contracts, loss from unconsolidated joint ventures, depreciation and amortization expense, transaction costs, payroll and related costs from management services contracts, corporate general and administrative expense, unrealized gain (loss) on non-real estate investment, gains (losses) from investments in securities, other income - assignment fee, interest and other income (loss), gain on sales-type lease, gains on sales of real estate, direct reimbursements of payroll and related costs from management services contracts and development and management services revenue are not included in NOI and are provided as reconciling items to the Company’s reconciliations of its share of NOI to net income.

The Company’s segments are based on the Company’s method of internal reporting which classifies its operations by geographic area. The Company’s segments by geographic area are Boston, Los Angeles, New York, San Francisco, Seattle and Washington, DC. On September 1, 2021, the Company invested in a joint venture that acquired Safeco Plaza located in Seattle, Washington. As such, the Seattle region was identified as a segment during the third quarter of 2021. The Company also presents information for each segment by property type, including Premier Workplace (which includes office, life sciences and retail), Residential and Hotel.

Information by geographic area and property type (dollars in thousands):

For the year ended December 31, 2023:


	Boston			Los Angeles			New York			San Francisco			Seattle			Washington, DC			Total
Rental Revenue: (1)
Premier Workplace	$	1,093,840		$	3,890		$	1,053,615		$	539,904		$	63,830		$	364,920		$	3,119,999
Residential	16,452			—			—			14,102			—			17,038			47,592
Hotel	47,357			—			—			—			—			—			47,357
Total	1,157,649			3,890			1,053,615			554,006			63,830			381,958			3,214,948
% of Grand Totals	36.01		%	0.12		%	32.77		%	17.23		%	1.99		%	11.88		%	100.00		%
Rental Expenses:
Premier Workplace	393,339			1,431			415,831			194,205			12,387			143,504			1,160,697
Residential	6,378			—			—			9,255			—			7,617			23,250
Hotel	32,225			—			—			—			—			—			32,225
Total	431,942			1,431			415,831			203,460			12,387			151,121			1,216,172
% of Grand Totals	35.51		%	0.12		%	34.19		%	16.73		%	1.02		%	12.43		%	100.00		%
Net operating income	$	725,707		$	2,459		$	637,784		$	350,546		$	51,443		$	230,837		$	1,998,776
% of Grand Totals	36.31		%	0.12		%	31.91		%	17.54		%	2.57		%	11.55		%	100.00		%
Less: Net operating income attributable to noncontrolling interests in property partnerships	(45,730)			—			(148,635)			—			—			—			(194,365)
Add: Company’s share of net operating income from unconsolidated joint ventures	34,376			48,818			14,314			16,203			7,494			39,490			160,695
Company’s share of net operating income	$	714,353		$	51,277		$	503,463		$	366,749		$	58,937		$	270,327		$	1,965,106
% of Grand Totals	36.35		%	2.61		%	25.62		%	18.66		%	3.00		%	13.76		%	100.00		%

_______________

For the year ended December 31, 2022:


	Boston			Los Angeles			New York			San Francisco			Seattle			Washington, DC			Total
Rental Revenue: (1)
Premier Workplace	$	1,005,156		$	—		$	1,031,479		$	534,397		$	31,978		$	365,402		$	2,968,412
Residential	15,086			—			—			14,769			—			27,326			57,181
Hotel	39,482			—			—			—			—			—			39,482
Total	1,059,724			—			1,031,479			549,166			31,978			392,728			3,065,075
% of Grand Totals	34.58		%	—		%	33.65		%	17.92		%	1.04		%	12.81		%	100.00		%
Rental Expenses:
Premier Workplace	360,218			—			391,293			183,353			8,386			135,237			1,078,487
Residential	5,961			—			—			11,371			—			12,251			29,583
Hotel	27,478			—			—			—			—			—			27,478
Total	393,657			—			391,293			194,724			8,386			147,488			1,135,548
% of Grand Totals	34.66		%	—		%	34.46		%	17.15		%	0.74		%	12.99		%	100.00		%
Net operating income	$	666,067		$	—		$	640,186		$	354,442		$	23,592		$	245,240		$	1,929,527
% of Grand Totals	34.52		%	—		%	33.18		%	18.37		%	1.22		%	12.71		%	100.00		%
Less: Net operating income attributable to noncontrolling interests in property partnerships	(45,822)			—			(145,990)			—			—			—			(191,812)
Add: Company’s share of net operating income from unconsolidated joint ventures	34,233			53,023			1,594			12,785			7,690			36,756			146,081
Company’s share of net operating income	$	654,478		$	53,023		$	495,790		$	367,227		$	31,282		$	281,996		$	1,883,796
% of Grand Totals	34.75		%	2.81		%	26.32		%	19.49		%	1.66		%	14.97		%	100.00		%

_______________

For the year ended December 31, 2021:


	Boston			Los Angeles			New York			San Francisco			Seattle			Washington, DC			Total
Rental Revenue: (1)
Premier Workplace	$	930,560		$	—		$	1,012,172		$	508,620		$	—		$	340,808		$	2,792,160
Residential	13,397			—			—			3,892			—			25,379			42,668
Hotel	13,609			—			—			—			—			—			13,609
Total	957,566			—			1,012,172			512,512			—			366,187			2,848,437
% of Grand Totals	33.62		%	—		%	35.53		%	17.99		%	—		%	12.86		%	100.00		%
Rental Expenses:
Premier Workplace	322,298			—			379,267			168,040			—			127,102			996,707
Residential	5,811			—			—			6,717			—			11,916			24,444
Hotel	12,998			—			—			—			—			—			12,998
Total	341,107			—			379,267			174,757			—			139,018			1,034,149
% of Grand Totals	32.98		%	—		%	36.67		%	16.90		%	—		%	13.45		%	100.00		%
Net operating income	$	616,459		$	—		$	632,905		$	337,755		$	—		$	227,169		$	1,814,288
% of Grand Totals	33.98		%	—		%	34.88		%	18.62		%	—		%	12.52		%	100.00		%
Less: Net operating income attributable to noncontrolling interests in property partnerships	(43,232)			—			(143,072)			—			—			—			(186,304)
Add: Company’s share of net operating income (loss) from unconsolidated joint ventures	16,551			51,641			(664)			14,152			2,498			23,578			107,756
Company’s share of net operating income	$	589,778		$	51,641		$	489,169		$	351,907		$	2,498		$	250,747		$	1,735,740
% of Grand Totals	33.98		%	2.98		%	28.18		%	20.27		%	0.14		%	14.45		%	100.00		%

_______________

The entire disclosure for reporting segments including data and tables. Reportable segments include those that meet any of the following quantitative thresholds a) it's reported revenue, including sales to external customers and intersegment sales or transfers is 10 percent or more of the combined revenue, internal and external, of all operating segments b) the absolute amount of its reported profit or loss is 10 percent or more of the greater, in absolute amount of 1) the combined reported profit of all operating segments that did not report a loss or 2) the combined reported loss of all operating segments that did report a loss c) its assets are 10 percent or more of the combined assets of all operating segments.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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Reference 3: http://www.xbrl.org/2003/role/disclosureRef
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Reference 4: http://www.xbrl.org/2003/role/disclosureRef
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Deferred Charges Schedule of Acquired In-Place Lease Intangibles (Details) $ in Thousands	Dec. 31, 2023 USD ($)
Goodwill and Intangible Assets Disclosure [Abstract]
2024	$ 52,489
2025	40,739
2026	27,095
2027	20,823
2028	$ 11,113

Cover - USD ($)	12 Months Ended
Cover - USD ($)	Dec. 31, 2023	Feb. 20, 2024	Jun. 30, 2023
Entity Information [Line Items]
Document Type	10-K
Document Annual Report	true
Document Period End Date	Dec. 31, 2023
Document Transition Report	false
Entity File Number	1-13087
Entity Registrant Name	BOSTON PROPERTIES, INC.
Entity Central Index Key	0001037540
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2023
Document Fiscal Period Focus	FY
Amendment Flag	false
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	04-2473675
Entity Address, Address Line One	Prudential Center, 800 Boylston Street, Suite 1900
Entity Address, City or Town	Boston
Entity Address, State or Province	MA
Entity Address, Postal Zip Code	02199-8103
City Area Code	617
Local Phone Number	236-3300
Title of 12(b) Security	Common Stock, par value $.01 per share
Entity Listing, Par Value Per Share	$ 0.01
Trading Symbol	BXP
Security Exchange Name	NYSE
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
ICFR Auditor Attestation Flag	true
Document Financial Statement Error Correction [Flag]	false
Entity Shell Company	false
Entity Public Float			$ 9,012,722,469
Documents Incorporated by Reference	Certain information contained in Boston Properties Inc.’s Proxy Statement relating to its Annual Meeting of Stockholders to be held May 22, 2024 is incorporated by reference in Items 10, 11, 12, 13 and 14 of Part III. Boston Properties, Inc. intends to file such Proxy Statement with the Securities and Exchange Commission not later than 120 days after the end of its fiscal year ended December 31, 2023.
Entity Common Stock, Shares Outstanding		157,010,980
Boston Properties Limited Partnership
Entity Information [Line Items]
Document Type	10-K
Document Period End Date	Dec. 31, 2023
Entity File Number	0-50209
Entity Registrant Name	BOSTON PROPERTIES LIMITED PARTNERSHIP
Entity Central Index Key	0001043121
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2023
Document Fiscal Period Focus	FY
Amendment Flag	false
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	04-3372948
Title of 12(g) Security	Units of Limited Partnership
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
ICFR Auditor Attestation Flag	true
Document Financial Statement Error Correction [Flag]	false
Entity Shell Company	false

Lessor Leases Narrative (Details) $ in Thousands	12 Months Ended
Lessor Leases Narrative (Details) $ in Thousands	Dec. 31, 2023 USD ($) ft² Real_Estate_Properties	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)
Lessor, Lease, Description [Line Items]
Gain on sales-type lease	$ 0	$ 10,058	$ 0
Lease Agreements
Lessor, Lease, Description [Line Items]
Net Rentable Area (in sf) \| ft²	367,338
Percent of Total	0.87%
Number of real estate properties	4
Hotel [Member]
Lessor, Lease, Description [Line Items]
Gain on sales-type lease		$ 10,100
Number of real estate properties \| Real_Estate_Properties	1
Lessor, Sales-type Lease, Option to Terminate	one non-cancelable ground lease obligation	one non-cancelable ground lease obligation
Direct Financing Lease, Interest Income	$ 900	$ 0

Investments in Unconsolidated Joint Ventures (Balance Sheets of the Unconsolidated Joint Ventures) (Details) - USD ($)
$ in Thousands

12 Months Ended

Dec. 31, 2023

Dec. 31, 2022

Dec. 31, 2021

ASSETS

$ 20,593,459

$ 19,496,442

26,026,149

24,207,669

Mortgage and notes payable, net

4,166,379

3,272,368

Members’/Partners’ equity

445,947

450,918

5,876,697

6,132,919

Carying value of the Company's investment in unconsolidated joint ventures

26,026,149

24,207,669

1,377,319

1,715,911

401,680

^[1]

237,510

^[1]

324,298

167,351

Lease Liabilities - Operating Leases

417,961

249,335

350,391

204,686

13,953

13,028

ASSETS

^[2]

5,811,763

6,537,554

Other assets

682,291

^[3]

756,786

6,494,054

7,294,340

Mortgage and notes payable, net

3,351,873

4,022,746

Members’/Partners’ equity

^[4]

361,357

716,271

2,780,824

2,555,323

Company's share of equity

6,494,054

7,294,340

1,278,483

1,238,929

Carying value of the Company's investment in unconsolidated joint ventures

^[5]

58,933

391,556

^[6]

1,337,416

1,630,485

248,900

20,100

21,200

Lease Liabilities - Operating Leases

382,200

30,500

(272,603)

^[7]

(50,705)

^[7]

$ 0

35,756

^[8]

$ 0

13,900

39,900

85,400

Colorado Center

Carying value of the Company's investment in unconsolidated joint ventures

298,906

301,820

^[9]

237,815

233,862

Carying value of the Company's investment in unconsolidated joint ventures

58,308

94,497

^[9]

75,718

120,083

200 Fifth Avenue JV LLC | Unconsolidated Joint Ventures [Member]

33,400

Gateway Commons Complex [Member]

33,400

Carying value of the Company's investment in unconsolidated joint ventures

48,971

47,808

^[9]

376,834

324,038

BP/CRF Metropolitan Square LLC [Member]

^[9]

37,629

35,800

Carying value of the Company's investment in unconsolidated joint ventures

(29,678)

(15)

^[9]

44,734

69,785

Safeco Plaza REIT LLC | Unconsolidated Joint Ventures [Member]

29,900

29,900

Carying value of the Company's investment in unconsolidated joint ventures

(116,534)

3,798

42,988

114,992

^[9]

360 PAS Holdco LLC | Unconsolidated Joint Ventures [Member]

54,000

54,000

Dock 72

^[9]

11,890

19,921

(95,521)

(98,980)

Platform 16

Carying value of the Company's investment in unconsolidated joint ventures

(143,052)

7,108

^[9]

45,564

$ 158,109

Platform 16 | Unconsolidated Joint Ventures [Member]

155,200

Consolidation, Variable Interest Entity, Policy

$ 155,200

[1]

See Note 4.

[2]

At December 31, 2022, this amount included right of use assets - finance leases totaling approximately $248.9 million. At December 31, 2023 and December 31, 2022, this amount included right of use assets - operating leases totaling approximately $20.1 million and $21.2 million, respectively.

[3]

At December 31, 2023, this amount included sales-type lease receivable, net totaling approximately $13.9 million.

[4]

At December 31, 2022, this amount included lease liabilities - finance leases totaling approximately $382.2 million. At December 31, 2023 and December 31, 2022, this amount included lease liabilities - operating leases totaling approximately $30.5 million.

[5]

This amount represents the aggregate difference between the Company’s historical cost basis and the basis reflected at the joint venture level, which is typically amortized over the life of the related assets and liabilities. Basis differentials


	December 31, 2023		December 31, 2022
Property	(in thousands)
Colorado Center	$	298,906	$	301,820
200 Fifth Avenue	58,308		94,497
Gateway Commons	48,971		47,808
Safeco Plaza	(29,678)		(15)
360 Park Avenue South	(116,534)		3,798
Dock 72	(95,521)		(98,980)
Platform 16	(143,052)		7,108

These basis differentials (excluding land) will be amortized over the remaining lives of the related assets and liabilities.

[6]

Investments with deficit balances aggregating approximately $39.9 million and $85.4 million at December 31, 2023 and December 31, 2022, respectively, are reflected within Other Liabilities in the Company’s Consolidated Balance Sheets.

[7]

During the year ended December 31, 2023, the Company recognized an other-than-temporary impairment loss on its investments in Platform 16, 360 Park Avenue South, 200 Fifth Avenue and Safeco Plaza of approximately $155.2 million, $54.0 million, $33.4 million and $29.9 million, respectively, as described below in this Note 6. During the year ended December 31, 2022, the Company recognized an other-than-temporary impairment loss on its investment in the unconsolidated joint venture that owns Dock 72 in Brooklyn, New York totaling approximately $50.7 million.

[8]

During the year ended December 31, 2023, the Company completed a restructuring of its ownership in Metropolitan Square, as described below in this Note 6.

[9]

Investments with deficit balances aggregating approximately $39.9 million and $85.4 million at December 31, 2023 and December 31, 2022, respectively, are included within Other Liabilities in the Company’s Consolidated Balance Sheets.

Organization (Details) ft² in Millions	12 Months Ended
Organization (Details) ft² in Millions	Dec. 31, 2023 ft² Real_Estate_Properties yr shares	Dec. 31, 2022
Real Estate Properties [Line Items]
Restriction on redemption of OP units from date of issuance (years) \| yr	1
One OP unit is equivalent to one share of Common Stock (in shares) \| shares	1
OP unit conversion rate (in shares) \| shares	1
Vesting Period	4 years
Number of VIEs	8
2012 OPP Units and Vested MYLTIPs
Real Estate Properties [Line Items]
Vesting Period	3 years
Variable Interest Entity, Primary Beneficiary [Member] \| Commercial Real Estate Properties [Member]
Real Estate Properties [Line Items]
Number of VIEs	5
Construction in Progress
Real Estate Properties [Line Items]
Number of real estate properties	10
Net Rentable Area (in sf) \| ft²	2.7
Commercial Real Estate Properties [Member]
Real Estate Properties [Line Items]
Number of real estate properties	188
Net Rentable Area (in sf) \| ft²	53.3
Office and Life Sciences Building [Member]
Real Estate Properties [Line Items]
Number of real estate properties	167
Office and Life Sciences Building [Member] \| Construction in Progress
Real Estate Properties [Line Items]
Number of real estate properties	7
Retail Site [Member]
Real Estate Properties [Line Items]
Number of real estate properties	14
Retail Site [Member] \| Construction in Progress
Real Estate Properties [Line Items]
Number of real estate properties	2
Residential Building
Real Estate Properties [Line Items]
Number of real estate properties	6
Residential Building \| Construction in Progress
Real Estate Properties [Line Items]
Number of real estate properties	1
Hotel [Member]
Real Estate Properties [Line Items]
Number of real estate properties	1
Boston Properties Limited Partnership
Real Estate Properties [Line Items]
General and limited partnership interest in the operating partnership (percent)	89.40%	89.60%

Derivative Instruments and Hedging Activities (Details) - Interest Rate Swap - USD ($) $ in Thousands			12 Months Ended
	Dec. 07, 2023	May 02, 2023	Dec. 31, 2023	Dec. 14, 2023	Dec. 31, 2022
Derivative [Line Items]
Derivative, Notional Amount	$ 600,000	$ 1,200,000	$ 2,100,000
Derivative, Maturity Date		May 16, 2024
Fair Value Hedge Assets			$ 1,976		$ 0
325 Main Street, 355 Main Street, 90 Broadway and Kendall Center Green Garage Properties [Member]
Derivative [Line Items]
Derivative, Swap Type			Interest Rate Swaps
Derivative, Notional Amount	$ 600,000		$ 600,000
Derivative, Maturity Date	Oct. 26, 2028		Oct. 26, 2028
Cash Flow Hedge Derivative Instrument Liabilities at Fair Value			$ (7,198)
Santa Monica Business Park [Member]
Derivative [Line Items]
Derivative, Swap Type			Interest Rate Swaps
Derivative, Notional Amount			$ 300,000	$ 300,000
Derivative, Maturity Date			Apr. 01, 2025
Fair Value Hedge Assets			$ 6,626
Three Two Five Main Street, Three Five Five Main Street, Ninety Broadway and Kendall Center Green Garage Properties and Unsecured Term Loan
Derivative [Line Items]
Derivative, Notional Amount			1,800,000
Cash Flow Hedge Derivative Instrument Liabilities at Fair Value			$ (4,650)
2023 Unsecured Term Loan
Derivative [Line Items]
Derivative, Swap Type			Interest Rate Swaps
Derivative, Notional Amount			$ 1,200,000
Derivative, Maturity Date			May 16, 2024
Fair Value Hedge Assets			$ 2,548
Minimum [Member] \| 325 Main Street, 355 Main Street, 90 Broadway and Kendall Center Green Garage Properties [Member]
Derivative [Line Items]
Derivative, Fixed Interest Rate			3.79%
Minimum [Member] \| Santa Monica Business Park [Member]
Derivative [Line Items]
Derivative, Fixed Interest Rate			2.661%
Minimum [Member] \| 2023 Unsecured Term Loan
Derivative [Line Items]
Derivative, Fixed Interest Rate			4.638%
Maximum [Member] \| 325 Main Street, 355 Main Street, 90 Broadway and Kendall Center Green Garage Properties [Member]
Derivative [Line Items]
Derivative, Fixed Interest Rate			3.798%
Maximum [Member] \| Santa Monica Business Park [Member]
Derivative [Line Items]
Derivative, Fixed Interest Rate			2.688%
Maximum [Member] \| 2023 Unsecured Term Loan
Derivative [Line Items]
Derivative, Fixed Interest Rate			4.646%

Stockholders' Equity / Partners' Capital Dividends / Distributions (Details) - $ / shares	Oct. 31, 2023	Jul. 31, 2023	Apr. 28, 2023	Jan. 30, 2023	Oct. 31, 2022	Jul. 29, 2022	Apr. 29, 2022	Jan. 28, 2022	Oct. 29, 2021	Jul. 30, 2021	Apr. 30, 2021	Feb. 16, 2021	Jan. 28, 2021	Dec. 18, 2023
Dividends / Distributions [Line Items]
Dividends Payable, Amount Per Share / Unit														$ 0.98
Common Stock / Unit, Dividends / Distributions, Per Share / Unit, Cash Paid	$ 0.98	$ 0.98	$ 0.98	$ 0.98	$ 0.98	$ 0.98	$ 0.98	$ 0.98	$ 0.98	$ 0.98	$ 0.98		$ 0.98
Boston Properties Limited Partnership
Dividends / Distributions [Line Items]
Dividends Payable, Amount Per Share / Unit														0.98
Common Stock / Unit, Dividends / Distributions, Per Share / Unit, Cash Paid	0.98	0.98	0.98	0.98	0.98	0.98	0.98	0.98	0.98	0.98	0.98		0.98
Boston Properties Limited Partnership \| Op units and LTIP units
Dividends / Distributions [Line Items]
Dividends Payable, Amount Per Share / Unit														0.98
Common Stock / Unit, Dividends / Distributions, Per Share / Unit, Cash Paid	0.98	0.98	0.98	0.98	0.98	0.98	0.98	0.98	0.98	0.98	0.98		0.98
Boston Properties Limited Partnership \| Unvested MYLTIP Units [Member]
Dividends / Distributions [Line Items]
Dividends Payable, Amount Per Share / Unit														$ 0.098
Common Stock / Unit, Dividends / Distributions, Per Share / Unit, Cash Paid	$ 0.098	$ 0.098	$ 0.098	$ 0.098	$ 0.098	$ 0.098	$ 0.098	$ 0.098	$ 0.098	$ 0.098	$ 0.098		$ 0.098
Series B Cumulative Redeemable Preferred Stock / Unit [Member]
Dividends / Distributions [Line Items]
Common Stock / Unit, Dividends / Distributions, Per Share / Unit, Cash Paid												$ 32.8125

Summary Of Significant Accounting Policies (Policies)

12 Months Ended

Dec. 31, 2023

Accounting Policies [Abstract]

Basis of Presentation

The accompanying consolidated financial statements are presented using the accrual basis of accounting in conformity with accounting principles generally accepted in the United States of America. BXP does not have any other significant assets, liabilities or operations, other than its investment in BPLP, nor does it have employees of its

own. BPLP, not BXP, generally executes all significant business relationships other than transactions involving securities of BXP. All majority-owned subsidiaries and joint ventures over which the Company has financial and operating control and variable interest entities (“VIEs”) in which the Company has determined it is the primary beneficiary are included in the consolidated financial statements. All significant intercompany balances and transactions have been eliminated in consolidation. The Company accounts for all other unconsolidated joint ventures using the equity method of accounting. Accordingly, the Company’s share of the earnings of these joint ventures and companies is included in consolidated net income.

Variable Interest Entities (VIEs)

Consolidated VIEs are those for which the Company is considered to be the primary beneficiary of a VIE. The primary beneficiary is the entity that has a controlling financial interest in the VIE, which is defined by the entity having both of the following characteristics: (1) the power to direct the activities that, when taken together, most significantly impact the VIE’s performance and (2) the obligation to absorb losses or the right to receive the returns from the VIE that could potentially be significant to the VIE. The assets of each VIE are only available to satisfy such VIE's respective liabilities. The Company has identified eight entities that are VIEs as of December 31, 2023 and has determined that it is the primary beneficiary for all of these entities as of December 31, 2023.

Real Estate

Depreciation is computed on a straight-line basis over the estimated useful lives of the assets as follows:


Land improvements						25 to 40 years
Buildings and improvements						10 to 40 years
Tenant improvements						Shorter of useful life or terms of related lease
Furniture, fixtures, and equipment						3 to 10 years

Cash and Cash Equivalents

Cash Held in Escrows

Investment in Securities

Investments in Securities

Non-Real Estate Investments

Tenant and Other Receivables and Notes Receivable

Tenant and Other Receivables

Tenant and other accounts receivable, other than accrued rents receivable, are expected to be collected within one year.

Notes Receivable

Deferred Charges

Investments in Unconsolidated Joint Ventures

The combined summarized financial information of the unconsolidated joint ventures is disclosed in Note 6.

Revenue Recognition


	Acquired Above-Market Lease Intangibles		Acquired Below-Market Lease Intangibles
2024	$	3,985	$	9,961
2025	1,880		9,756
2026	982		8,602
2027	743		5,432
2028	605		2,125

Lessee, Leases

Lessee

•observable mortgage rates spread over U.S. Treasury issuances, and

•unlevered property yields and discount rates.

The Company then applied adjustments to account for considerations related to term and interpolated the IBR.

Lessor, Leases

Lessor

Operating Leases

Recoveries from tenants, consisting of amounts due from tenants for common area maintenance, real estate taxes and other recoverable costs, are recognized as revenue in the period during which the expenses are incurred. The Company recognizes these reimbursements on a gross basis, as the Company obtains control of the goods and services before they are transferred to the tenant.

In addition, in accordance with ASC 842, lessors will only capitalize incremental direct leasing costs.

Sales-Type Leases

Earnings Per Share and Earnings Per Common Unit

Earnings Per Share

Earnings Per Common Unit

could occur from units issuable in connection with awards under BXP’s stock-based compensation plans, including upon the exercise of stock options, and conversion of preferred units of BPLP.

Fair Value of Financial Instruments


Financial Instrument			Level
3-Month United States treasury bills			Level 1
Investment in securities (1)			Level 1
Non-real estate investments (1) (2)			Level 2
Unsecured senior notes (3)			Level 1
Related party note receivable			Level 3
Notes receivable			Level 3
Sales-type lease receivable			Level 3
Mortgage notes payable			Level 3
Unsecured line of credit			Level 3
Unsecured term loan			Level 3

_______________

(1)See “Investments in Securities” and “Non-Real Estate Investments” policies above for information on their fair values.

(2)Included within Prepaid and Other Assets on the Consolidated Balance Sheets.

(3)If trading volume for the period is low, the valuation could be categorized as Level 2.

Non-Recurring Fair Value


	December 31, 2023				December 31, 2022
	Carrying Amount		Estimated Fair Value		Carrying Amount		Estimated Fair Value
3-Month United States Treasury Bills (1)	$	302,746	$	302,746	$	—	$	—

Related party note receivable, net	$	88,779	$	90,593	$	78,576	$	79,220
Note receivable, net	1,714		1,677		—		—
Sales-type lease receivable, net	13,704		13,338		12,811		13,045
Total	$	104,197	$	105,608	$	91,387	$	92,265

Mortgage notes payable, net	$	4,166,379	$	3,705,513	$	3,272,368	$	2,744,479
Unsecured senior notes, net	10,491,617		9,697,393		10,237,968		9,135,512
Unsecured line of credit	—		—		—		—
Unsecured term loan, net	1,198,301		1,196,945		730,000		730,000
Total	$	15,856,297	$	14,599,851	$	14,240,336	$	12,609,991

_______________

Recurring Fair Value

The following table presents the aggregate fair value of the Company’s interest rate swaps as of December 31, 2023 and December 31, 2022 (in thousands):


Fair value	December 31, 2023		December 31, 2022
Interest rate swaps	$	1,976	$	—

Derivative Instruments and Hedging Activities

Stock-Based Employee Compensation Plans

Use of Estimates in the Preparation of Financial Statements

Equity Offering Costs

Underwriting commissions and offering costs have been reflected as a reduction of additional paid-in capital.

Treasury Stock

BXP’s share repurchases are reflected as treasury stock utilizing the cost method of accounting and are presented as a reduction to consolidated stockholders’ equity.

Dividends

Income Taxes

BPLP

Income Taxes

New Accounting Pronouncements

Newly Issued Accounting Pronouncements

Stockholders' Equity / Partners' Capital (Tables)

12 Months Ended

Dec. 31, 2023

Class of Stock [Line Items]

Dividends Declared [Table Text Block]

The following table presents BXP’s dividends per share and BPLP’s distributions per OP Unit and LTIP Unit paid or declared during the years ended December 31, 2023, 2022 and 2021:


Record Date	Payment Date	Dividend (Per Share)	Distribution (Per Unit)
December 29, 2023	January 30, 2024	$0.98	$0.98
September 29, 2023	October 31, 2023	$0.98	$0.98
June 30, 2023	July 31, 2023	$0.98	$0.98
March 31, 2023	April 28, 2023	$0.98	$0.98
December 30, 2022	January 30, 2023	$0.98	$0.98
September 30, 2022	October 31, 2022	$0.98	$0.98
June 30, 2022	July 29, 2022	$0.98	$0.98
March 31, 2022	April 29, 2022	$0.98	$0.98
December 31, 2021	January 28, 2022	$0.98	$0.98
September 30, 2021	October 29, 2021	$0.98	$0.98
June 30, 2021	July 30, 2021	$0.98	$0.98
March 31, 2021	April 30, 2021	$0.98	$0.98
December 31, 2020	January 28, 2021	$0.98	$0.98

Series B Preferred Stock [Member]

Class of Stock [Line Items]

Dividends Declared [Table Text Block]

The following table presents BXP’s dividend per share on its Series B Preferred Stock paid during the year ended December 31, 2021:

Record Date

Payment Date

Dividend (Per Share)

February 5, 2021

February 16, 2021

$32.8125

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Goodwill and Intangible Assets Disclosure [Abstract]

Summary Of Significant Accounting Policies Schedule of Estimated Useful Lives (Details)	Dec. 31, 2023
Tenant improvements
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Estimated Useful Lives
Minimum [Member] \| Land Improvements
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	25 years
Minimum [Member] \| Buildings and improvements
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	10 years
Minimum [Member] \| Furniture, fixtures, and equipment
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	3 years
Maximum [Member] \| Land Improvements
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	40 years
Maximum [Member] \| Buildings and improvements
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	40 years
Maximum [Member] \| Furniture, fixtures, and equipment
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	10 years

Deferred Charges (Tables)

12 Months Ended

Dec. 31, 2023

Deferred Costs

Deferred charges consisted of the following at December 31, 2023 and 2022 (in thousands):


	December 31, 2023		December 31, 2022
Leasing costs, including lease related intangibles	$	1,168,940	$	1,095,231
Financing costs	20,600		19,311
	1,189,540		1,114,542
Less: Accumulated amortization	(429,119)		(381,260)
	$	760,421	$	733,282

Finite-lived Intangible Assets Amortization Expense

The following table summarizes the scheduled amortization of the Company’s acquired in-place lease intangibles for each of the five succeeding years (in thousands).


	Acquired In-Place Lease Intangibles
2024	$	52,489
2025	40,739
2026	27,095
2027	20,823
2028	11,113

Summary Of Significant Accounting Policies (Carrying Value Of Indebtedness And Corresponding Estimate Of Fair Value) (Details) - USD ($)
$ in Thousands

Dec. 31, 2023

Dec. 31, 2022

Summary Of Significant Accounting Policies [Line Items]

$ 1,714

$ 0

13,704

12,811

4,166,379

3,272,368

10,491,617

10,237,968

1,198,301

730,000

Summary Of Significant Accounting Policies [Line Items]

88,779

78,576

Carrying Amount [Member]

^[1]

302,746

13,704

12,811

104,197

91,387

4,166,379

3,272,368

10,491,617

10,237,968

1,198,301

730,000

Carrying Amount [Member] | Related Party

15,856,297

14,240,336

Summary Of Significant Accounting Policies [Line Items]

Carrying Amount [Member] | Nonrelated Party

88,779

78,576

Summary Of Significant Accounting Policies [Line Items]

Estimated Fair Value [Member]

1,714

Summary Of Significant Accounting Policies [Line Items]

^[1]

302,746

13,338

13,045

105,608

92,265

3,705,513

2,744,479

9,697,393

9,135,512

1,196,945

730,000

Estimated Fair Value [Member] | Related Party

14,599,851

12,609,991

Summary Of Significant Accounting Policies [Line Items]

Estimated Fair Value [Member] | Nonrelated Party

90,593

79,220

Summary Of Significant Accounting Policies [Line Items]

Lessee, Operating Lease, Liability, Payment, Due [Abstract]

$ 1,677

$ 0

[1]	Per the guidance in ASC 326, the Company concluded that the risk of nonpayment is nonexistent because the U.S. Government has a long history with no credit losses and therefore, no credit loss allowance was recorded.

Lease Liability Maturity Schedule Prior Year (Details) - USD ($)
$ in Thousands

Dec. 31, 2023

Dec. 31, 2022

2023

$ 29,989

$ 22,415

35,733

22,274

10,100

10,308

9,885

10,100

14,637

9,885

3,546,537

528,915

3,646,881

603,897

Lease Liabilities - Operating Leases

(3,296,490)

(399,211)

350,391

204,686

Finance Lease, Liability, Payment, Due [Abstract]

2023

70,370

^[1]

9,306

32,232

49,343

^[2]

31,972

9,971

32,170

10,166

118,232

^[1]

10,364

1,342,174

1,352,647

1,627,150

1,441,797

(1,209,189)

(1,192,462)

Derivative Instruments and Hedging Activities Disclosure [Abstract]

$ 417,961

$ 249,335

[1]	Finance lease payments in 2024 and 2028 include approximately $38.7 million and $105.3 million, respectively, related to purchase options that the Company was reasonably certain it would exercise upon execution of the ground leases. There can be no assurance that the Company will ultimately exercise the purchase options on the schedule currently contemplated or at all.
[2]	Finance lease payments in 2024 include approximately $38.7 million related to a purchase option that the Company was reasonably certain it would exercise upon execution of the ground lease. There can be no assurance that the Company will ultimately exercise the purchase options on the schedule currently contemplated.

Derivative Instruments and Hedging Activities

12 Months Ended

Dec. 31, 2023

Derivative Instruments and Hedging Activities Disclosure

8. Derivative Instruments and Hedging Activities

BPLP’s agreements with the swap derivative counterparties contain provisions whereby if BPLP defaults on the underlying indebtedness, including defaults where repayment of the indebtedness has not been accelerated by the lender, then BPLP could also be declared in default of the swap derivative obligation. As of December 31, 2023, the Company had not posted any collateral related to the agreements.

Effective Hedge Instruments

On May 2, 2023, BPLP entered into four interest rate swap contracts with notional amounts aggregating $1.2 billion. BPLP entered into these interest rate swap contracts to reduce its exposure to the variability in future cash flows attributable to changes in the 2023 Unsecured Term Loan interest rate. These interest rate swaps were entered into to fix Term SOFR, the reference rate for BPLP’s 2023 Unsecured Term Loan, at a weighted-average rate of 4.6420% for the period commencing on May 4, 2023 and ending on May 16, 2024 (see Note 7). For the period from May 4, 2023 through December 31, 2023, the Company recognized approximately $(4.2) million of interest expense related to its interest rate swap contracts.

On December 7, 2023, BPLP entered into three interest rate swap contracts with notional amounts aggregating $600.0 million. BPLP entered into these interest rate swap contracts to reduce its exposure to the variability in future cash flows attributable to changes in the interest rate associated with the $600.0 million mortgage secured by its 325 Main Street, 355 Main Street, 90 Broadway and Cambridge East Garage (also known as Kendall Center Green Garage) properties (see Note 7). These interest rate swaps were entered into to fix Daily Compounded SOFR, the reference rate for the mortgage, at a weighted-average fixed interest rate of 3.7925% for the period commencing on December 15, 2023 and ending on October 26, 2028, for an all in interest rate of 6.04% per annum. For the period from December 15, 2023 through December 31, 2023, the Company recognized approximately $(0.4) million of interest expense related to these interest rate swap contracts.

On December 14, 2023, the Company completed the acquisition of it’s joint venture partner’s 45% interest in the joint venture entity that owns Santa Monica Business Park located in Santa Monica, California (See Note 3). The property is subject to $300.0 million of mortgage debt (see Note 7). Prior to the Company’s acquisition, the borrower under the loan, SMBP LLC entered into three interest rate swap contracts with notional amounts aggregating $300.0 million to fix SOFR, the reference rate for the mortgage loan, at a weighted-average fixed interest rate of approximately 2.679% per annum for a period that ends on April 1, 2025. The Company acquired and elected to continue with hedge accounting for these swaps. Upon acquisition, the Company recorded the interest rate swaps at their fair value of approximately $7.3 million. These interest rate swap contracts were entered into to reduce the exposure to the variability in future cash flows attributable to changes in the interest rate associated with the mortgage loan. For the period from December 14, 2023 through December 31, 2023, the Company recognized approximately $(0.4) million of interest expense related to these interest rate swap contracts.

BPLP assesses the effectiveness of its hedges both at inception and on an ongoing basis. If the hedges are deemed to be effective, the fair value is recorded in “Accumulated other comprehensive income (loss)” in the Company’s Consolidated Balance Sheets and is subsequently reclassified into “Interest expense” in the Company’s

Consolidated Statements of Operations in the period that the hedged forecasted transactions affect earnings. BPLP’s derivative financial instruments are cash flow hedges that are designated as effective hedges, and are carried at their estimated fair value on a recurring basis (See Note 2). The Company did not incur any ineffectiveness during the year ended December 31, 2023.

BPLP’s and SMBP LLC’s interest rate swap contracts consisted of the following at December 31, 2023 (dollars in thousands):


Derivative Instrument	Aggregate Notional Amount				Strike Rate Range					Balance Sheet Location
			Effective Date	Maturity Date	Low			High			Fair Value
BPLP:
Interest Rate Swaps	$	1,200,000	May 4, 2023	May 16, 2024	4.638	%	—	4.646	%	Prepaid expenses and other assets	$	2,548
Interest Rate Swaps	600,000		December 15, 2023	October 26, 2028	3.790	%	—	3.798	%	Other liabilities	(7,198)
	1,800,000										(4,650)
SMBP LLC
Interest Rate Swaps	300,000		December 14, 2023	April 1, 2025	2.661	%	—	2.688	%	Prepaid expenses and other assets	6,626
	$	2,100,000									$	1,976

The following table presents the location in the financial statements of the gains or losses recognized related to the Company’s cash flow hedges for the years ended December 31, 2023, 2022 and 2021 (in thousands):


	Year ended December 31,
		2023		2022		2021
Amount of gain (loss) related to the effective portion recognized in other comprehensive income (1)		$	(14,405)	$	19,396	$	8,544
Amount of gain (loss) related to the effective portion subsequently reclassified to earnings (2)		$	6,703	$	6,707	$	6,704
Amount of gain (loss) relate do the ineffective portion and amount excluded from effectiveness testing		$	—	$	—	$	—

_______________

(1)Includes the Company’s share of gain (loss) related to the effective portion of derivatives outstanding at its unconsolidated joint venture properties.

(2)Consists of amounts from previous interest rate programs.

BPLP has formally documented all of its relationships between hedge instruments and hedging items, as well as its risk-management objectives and strategy for undertaking various hedge transactions. While management believes its judgments are reasonable, a change in a derivative's effectiveness as a hedge could materially affect expenses, net income (loss) and equity.

Ineffective Hedging Instruments

During the year ended December 31, 2023, to satisfy a lender requirement, the Company entered into two agreements with the same third-party to purchase and sell a $600.0 million interest rate cap. The Company did not elect hedge accounting, and as such, any change in market value will be recognized in Losses from interest rate contracts in the Consolidated Statement of Operations. For the year ended December 31, 2023, the Company recognized approximately $79,000 of loss from entering into these agreements

Summary Of Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2023

Summary Of Significant Accounting Policies [Line Items]

Property, Plant and Equipment

Depreciation is computed on a straight-line basis over the estimated useful lives of the assets as follows:


Land improvements						25 to 40 years
Buildings and improvements						10 to 40 years
Tenant improvements						Shorter of useful life or terms of related lease
Furniture, fixtures, and equipment						3 to 10 years

Schedule of Finite-Lived Intangible Assets, Future Amortization Expense

The following table summarizes the scheduled amortization of the Company’s acquired “above-” and “below-market” lease intangibles for each of the five succeeding years (in thousands).


	Acquired Above-Market Lease Intangibles		Acquired Below-Market Lease Intangibles
2024	$	3,985	$	9,961
2025	1,880		9,756
2026	982		8,602
2027	743		5,432
2028	605		2,125

Fair Value Measurement Inputs and Valuation Techniques [Table Text Block]

Fair Value of Financial Instruments


Financial Instrument			Level
3-Month United States treasury bills			Level 1
Investment in securities (1)			Level 1
Non-real estate investments (1) (2)			Level 2
Unsecured senior notes (3)			Level 1
Related party note receivable			Level 3
Notes receivable			Level 3
Sales-type lease receivable			Level 3
Mortgage notes payable			Level 3
Unsecured line of credit			Level 3
Unsecured term loan			Level 3

_______________

(1)See “Investments in Securities” and “Non-Real Estate Investments” policies above for information on their fair values.

(2)Included within Prepaid and Other Assets on the Consolidated Balance Sheets.

(3)If trading volume for the period is low, the valuation could be categorized as Level 2.

Fair Value, by Balance Sheet Grouping [Table Text Block]


	December 31, 2023				December 31, 2022
	Carrying Amount		Estimated Fair Value		Carrying Amount		Estimated Fair Value
3-Month United States Treasury Bills (1)	$	302,746	$	302,746	$	—	$	—

Related party note receivable, net	$	88,779	$	90,593	$	78,576	$	79,220
Note receivable, net	1,714		1,677		—		—
Sales-type lease receivable, net	13,704		13,338		12,811		13,045
Total	$	104,197	$	105,608	$	91,387	$	92,265

Mortgage notes payable, net	$	4,166,379	$	3,705,513	$	3,272,368	$	2,744,479
Unsecured senior notes, net	10,491,617		9,697,393		10,237,968		9,135,512
Unsecured line of credit	—		—		—		—
Unsecured term loan, net	1,198,301		1,196,945		730,000		730,000
Total	$	15,856,297	$	14,599,851	$	14,240,336	$	12,609,991

_______________

Schedule of Derivative Assets at Fair Value [Table Text Block]

The following table presents the aggregate fair value of the Company’s interest rate swaps as of December 31, 2023 and December 31, 2022 (in thousands):


Fair value	December 31, 2023		December 31, 2022
Interest rate swaps	$	1,976	$	—

Dividends Declared

The following table presents BXP’s dividends per share and BPLP’s distributions per OP Unit and LTIP Unit paid or declared during the years ended December 31, 2023, 2022 and 2021:


Record Date	Payment Date	Dividend (Per Share)	Distribution (Per Unit)
December 29, 2023	January 30, 2024	$0.98	$0.98
September 29, 2023	October 31, 2023	$0.98	$0.98
June 30, 2023	July 31, 2023	$0.98	$0.98
March 31, 2023	April 28, 2023	$0.98	$0.98
December 30, 2022	January 30, 2023	$0.98	$0.98
September 30, 2022	October 31, 2022	$0.98	$0.98
June 30, 2022	July 29, 2022	$0.98	$0.98
March 31, 2022	April 29, 2022	$0.98	$0.98
December 31, 2021	January 28, 2022	$0.98	$0.98
September 30, 2021	October 29, 2021	$0.98	$0.98
June 30, 2021	July 30, 2021	$0.98	$0.98
March 31, 2021	April 30, 2021	$0.98	$0.98
December 31, 2020	January 28, 2021	$0.98	$0.98

Dividend Paid [Member]

Summary Of Significant Accounting Policies [Line Items]

Dividends Declared

The tax treatment of common dividends per share for federal income tax purposes is as follows:


	For the year ended December 31,
	2023					2022					2021
	Per Share			%		Per Share			%		Per Share			%
Ordinary income	$	3.04		72.98	%	$	3.42		86.60	%	$	2.90		73.86	%
Capital gain income	1.12			27.02	%	0.53			13.40	%	0.57			14.57	%
Return of capital	—			—	%	—			—	%	0.45			11.57	%
Total	$	4.16	(1)	100.00	%	$	3.95	(2)	100.00	%	$	3.92	(3)	100.00	%

_____________

(3)The fourth quarter 2021 regular quarterly dividend was $0.98 per common share, all of which was allocable to 2022.

Lessee - Leases Narrative (Details)
$ in Thousands

1 Months Ended

12 Months Ended

21 Months Ended

Dec. 14, 2023

USD ($)

ft²

Aug. 01, 2023

USD ($)

ft²

Dec. 31, 2023

USD ($)

Dec. 31, 2023

USD ($)

Dec. 31, 2022

USD ($)

Dec. 31, 2021

USD ($)

Sep. 30, 2023

USD ($)

Dec. 13, 2023

Number of Properties Subject to Ground Leases

Lessee, Operating Lease, Option to Terminate

one cancelable and four non-cancelable ground lease obligations

four non-cancelable

Operating Lease, Payments

$ 121

$ (125)

$ 23,599

Operating Lease, Liability

^[1]

$ 324,298

324,298

167,351

350,391

204,686

Operating lease costs

^[2]

14,451

12,700

13,151

Right-of-Use Asset Obtained in Exchange for Finance Lease Liability

417,961

249,335

163,056

Interest on lease liabilities

^[3]

13,747

3,236

$ 2,471

Finance Lease, Right-of-Use Asset

401,680

$ 237,510

Lessee, Operating Lease, Variable Lease Payment, Terms and Conditions

no ground leases were subject to variable payments

Lessee, Operating Lease, Option to Extend

no ground leases were subject to variable payments and extension options

Joint Venture Partner [Member] | Santa Monica Business Park [Member]

^[4]

55.00%

343 Madison Avenue | Consolidated Entities

45.00%

Consolidated Entities, Ownership Percentage

55.00%

Lessee, Operating Lease, Term of Contract

99 years

Operating Leases, Future Minimum Payments, Due in Two Years

$ 21,800

Operating Leases, Future Minimum Payments, Due in Five Years

$ 10,900

Lessee, Operating Lease Payment Increase (Decrease) Term, Year

5 years

Lessee, Operating Lease Payment Increase (Decrease), Percentage

1.10

Lessee, Operating Lease, Discount Rate

8.14%

Net Present Value and Operating Lease Liability

$ 141,100

Operating Lease, Payments

10,000

$ 15,000

$ 25,000

Operating lease costs

$ 12,600

Finance Lease, Right-of-Use Asset

$ 166,800

Land Subject to Ground Leases | ft²

25,000

343 Madison Avenue | Consolidated Entities | Scenario, Plan

343 Madison Avenue | Consolidated Entities | Construction | Scenario, Plan

Recovery of Direct Costs

$ 117,000

900,000

Land subject to ground lease, percentage

70.00%

Lessee, Finance Lease, Number of Renewal Terms

Lessee, Finance Lease, Renewal Term

11 years

Lessee, Finance Lease, Option to Extend

The ground lease has an expiration date of February 4, 2054 with the option to renew the term for four additional periods of 11 years each, subject to certain conditions.

Lessee, finance lease, payment increase (decrease) frequency (in years)

5 years

Lessee, Finance Lease, Variable Lease Payment, Terms and Conditions

The ground lease requires monthly rental payments with increases every five years, starting in 2028.

Lessee, finance lease, purchase option frequency (in years)

15 years

Right-of-Use Asset Obtained in Exchange for Finance Lease Liability

$ 163,100

$ 164,100

Interest on lease liabilities

$ 400

Lessee, Finance Lease, Discount Rate

5.79%

Land Subject to Ground Leases | a

Santa Monica Business Park [Member] | Ground Lease

1,200,000

Santa Monica Business Park [Member] | Ground Lease | Unconsolidated Properties

Lease Intangibles

$ (46,659)

Santa Monica Business Park [Member] | Santa Monica Business Park [Member] | Unconsolidated Properties

Lease Intangibles

$ 46,700

55.00%

[1]	See Note 4.
[2]	One of the operating leases relate to assets under development for a portion of the year ended December 31, 2023 and as such, the operating lease costs were capitalized. For December 31, 2022 and 2021, no operating leases related to assets under development.
[3]	One, one and two of the finance leases relate to assets under development for all or a portion of the years ended December 31, 2023, December 31, 2022 and December 31, 2021, respectively, and as such, a portion of the interest amount was capitalized.
[4]	During the year ended December 31, 2023, the Company completed the acquisition of its joint venture partner’s 45% ownership interest in Santa Monica Business Park, as described below in this Note 6 and Note 3.

Derivative Instruments and Hedging Activities (Narrative) (Details)
$ in Thousands

1 Months Ended

8 Months Ended

12 Months Ended

Dec. 14, 2023

USD ($)

Dec. 07, 2023

USD ($)

Rate

May 02, 2023

USD ($)

Dec. 31, 2023

USD ($)

Dec. 31, 2023

USD ($)

Dec. 31, 2023

USD ($)

Dec. 31, 2023

USD ($)

Dec. 31, 2022

USD ($)

Dec. 31, 2021

USD ($)

Oct. 26, 2023

USD ($)

$ 579,572

$ 437,139

$ 423,346

Interest rate swaps recorded upon consolidation

(79)

(7,337)

$ 0

Joint Venture Partner [Member] | Santa Monica Business Park [Member]

^[1]

55.00%

Santa Monica Business Park [Member] | Mortgages [Member]

45.00%

Santa Monica Business Park [Member] | Mortgages [Member] | Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate

$ 300,000

325 Main Street, 355 Main Street, 90 Broadway and Kendall Center Green Garage Properties [Member] | Mortgages [Member]

300,000

Derivative, All in interest rate | Rate

$ 600,000

6.04%

Interest Rate Swap

Derivative, Inception Date

May 02, 2023

Derivative, Average Fixed Interest Rate

$ 600,000

$ 1,200,000

$ 2,100,000

2,100,000

4.642%

Derivative, Maturity Date

May 16, 2024

Interest Rate Swap | Santa Monica Business Park [Member]

(4,200)

Derivative, Average Fixed Interest Rate

$ 300,000

300,000

$ 300,000

2.679%

Derivative, Maturity Date

Apr. 01, 2025

Interest rate swaps recorded upon consolidation

(400)

$ 7,300

Interest Rate Swap | 325 Main Street, 355 Main Street, 90 Broadway and Kendall Center Green Garage Properties [Member]

Derivative, Inception Date

Dec. 07, 2023

Derivative, Average Fixed Interest Rate

$ 600,000

600,000

$ 600,000

3.7925%

Derivative, Maturity Date

Oct. 26, 2028

Goodwill and Intangible Assets Disclosure [Abstract]

$ (400)

[1]	During the year ended December 31, 2023, the Company completed the acquisition of its joint venture partner’s 45% ownership interest in Santa Monica Business Park, as described below in this Note 6 and Note 3.

Deferred Charges

12 Months Ended

Dec. 31, 2023

Deferred Charges

5. Deferred Charges

Deferred charges consisted of the following at December 31, 2023 and 2022 (in thousands):


	December 31, 2023		December 31, 2022
Leasing costs, including lease related intangibles	$	1,168,940	$	1,095,231
Financing costs	20,600		19,311
	1,189,540		1,114,542
Less: Accumulated amortization	(429,119)		(381,260)
	$	760,421	$	733,282

The following table summarizes the scheduled amortization of the Company’s acquired in-place lease intangibles for each of the five succeeding years (in thousands).


	Acquired In-Place Lease Intangibles
2024	$	52,489
2025	40,739
2026	27,095
2027	20,823
2028	11,113

Schedule of Aggregate Principal Payments on Mortgage Notes (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Debt Instrument [Line Items]
Deferred financing costs, net	$ (33,600)
Mortgage notes payable, net (amounts related to VIEs of $3,277,185 and $3,272,368 at December 31, 2023 and December 31, 2022, respectively)	4,166,379	$ 3,272,368
Mortgages [Member]
Debt Instrument [Line Items]
2024	0
2025	300,000
2026	0
2027	2,300,000
2028	600,000
Thereafter	1,000,000
Total	4,200,000
Deferred financing costs, net	29,270
Fair Value Debt Adjustment	4,351
Mortgage notes payable, net (amounts related to VIEs of $3,277,185 and $3,272,368 at December 31, 2023 and December 31, 2022, respectively)	$ 4,166,379	$ 3,300,000

Related Party Disclosures	12 Months Ended
Related Party Disclosures	Dec. 31, 2023
Related Party Transactions [Abstract]
Related Party Transactions Disclosure	16. Related Party Transactions Raymond A. Ritchey’s brother was employed by a real estate brokerage firm and participated in brokerage activities for which the Company paid the firm approximately $0.5 million, $1.6 million and $1.9 million for the years ended December 31, 2023, 2022 and 2021, respectively. The Company’s contract with this real estate brokerage firm ended on February 1, 2023 and as a result, it will not pay any further leasing commission to Mr. Ritchey’s brother. Mr. Ritchey is a Senior Executive Vice President of BXP. On June 5, 2023, a joint venture in which the Company owns a 30% interest repaid the construction loan collateralized by its 500 North Capitol Street, NW property and obtained new mortgage loans with related parties. The new mortgage loans have an aggregate principal balance of $105.0 million, bear interest at a weighted average fixed rate of 6.83% per annum and mature on June 5, 2026 (see Note 6). The Company funded $10.5 million of the refinancing at a fixed rate equal to 8.03% per annum. The loan has been reflected as a Related Party Note Receivable, Net on the Company’s Consolidated Balance Sheets. The Company has recognized interest income of approximately $0.6 million for the year ended December 31, 2023. 500 North Capitol Street, NW is an approximately 231,000 net rentable square foot premier workplace in Washington, DC. On July 13, 2018, the Company entered into a joint venture with a third party to acquire a development site at 3 Hudson Boulevard that, upon the future acquisition of additional available development rights, can accommodate an office tower with up to 2.0 million net rentable square feet located on the entire square block between 11th Avenue and Hudson Boulevard Park from West 34th Street to West 35th Street in New York City. The Company owns a 25% interest in, and is the managing member of, the joint venture. The Company provided $80.0 million of mortgage financing to the joint venture that bears interest at a variable rate equal to Term SOFR plus approximately 3.61% per annum and matures on February 9, 2024 (see Note 6 and 17). The loan has been reflected as a Related Party Note Receivable, Net on the Company’s Consolidated Balance Sheets. The Company has recognized interest income of approximately $8.9 million, $5.6 million and $3.6 million for the years ended December 31, 2023, 2022 and 2021, respectively. The Company's policy is to record notes receivable at their unamortized cost, net of any unamortized deferred fees or costs, premiums or discounts and an allowance for credit losses. Loan fees and direct costs associated with loans originated by the Company are deferred and amortized over the term of the note as interest income. In accordance with the 2021 Plan, and as approved by its Board of Directors, eight non-employee directors made elections to receive deferred stock units in lieu of cash fees for 2023. As a result of these elections, the aggregate cash fees otherwise payable to a non-employee director during a fiscal quarter are converted into a number of deferred stock units equal to the aggregate cash fees divided by the last reported sales price of a share of BXP’s Common Stock on the last trading of the applicable fiscal quarter. The deferred stock units are also credited with dividend equivalents as dividends are paid by BXP. The deferred stock units may be settled in shares of BXP’s Common Stock upon the cessation of such director’s service on the Board of Directors of BXP. The non-employee director compensation program provides, subject to certain conditions, the non-employee directors holding deferred stock units with the ability to elect, following cessation of their service on BXP’s Board of Directors, to diversify their investment elections into non-employer securities on a pre-tax basis and receive tax-deferred returns on such deferrals, which will ultimately be settled in cash. The Company’s obligation under the plan is that of an unsecured promise to pay the deferred compensation to the non-employee director in the future. At December 31, 2023 and 2022, the Company had maintained approximately $0.8 million and $0.6 million, respectively, in a separate account, which is not restricted as to its use. The Company’s liability under the plan is equal to the total amount of compensation deferred by the non-employee director and earnings on the deferred compensation pursuant to investments elected by the non-employee director. The Company’s liability as of December 31, 2023 and 2022 was approximately $0.8 million and $0.6 million, respectively, which is included in the accompanying Consolidated Balance Sheets. The terms of the non-employee director compensation program require the classification of these deferred stock units as temporary equity on the Consolidated Balance Sheets of Boston Properties, Inc. and Boston Properties Limited Partnership within Redeemable Deferred Stock Units. On December 16, 2021, in connection with the resignation of a director’s service on the Board of Directors of BXP, BXP issued 498 shares of Common Stock in settlement of the director’s outstanding deferred stock units. At December 31, 2023 and 2022, BXP had outstanding 119,471 and 97,853 deferred stock units, respectively.

The entire disclosure for related party transactions. Examples of related party transactions include transactions between (a) a parent company and its subsidiary; (b) subsidiaries of a common parent; (c) and entity and its principal owners; and (d) affiliates.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480990/946-20-50-2

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 5
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480990/946-20-50-5

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 6
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480990/946-20-50-6

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 235
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481062/946-235-50-2

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 235
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (e)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481062/946-235-50-2

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Topic 850
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483326/850-10-50-1

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 220
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.6-07(2)(g)(3))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483575/946-220-S99-1

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 220
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.6-07(2)(c))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483575/946-220-S99-1

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 220
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.6-07(2)(e))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483575/946-220-S99-1

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Topic 850
-Name Accounting Standards Codification
-Publisher FASB
-URI https://asc.fasb.org//850/tableOfContent

Reference 11: http://www.xbrl.org/2003/role/disclosureRef
-Topic 850
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 6
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483326/850-10-50-6

Reference 12: http://www.xbrl.org/2003/role/disclosureRef
-Topic 850
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483326/850-10-50-1

Reference 13: http://www.xbrl.org/2003/role/disclosureRef
-Topic 850
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483326/850-10-50-1

Lessee, Operating Lease, Liability, Payment, Due [Abstract]

Lease Liability Maturity Schedule (Details) - USD ($)
$ in Thousands

Dec. 31, 2023

Dec. 14, 2023

Dec. 31, 2022

$ 29,989

$ 22,415

35,733

22,274

10,100

10,308

9,885

10,100

2028

14,637

9,885

3,546,537

528,915

3,646,881

603,897

Operating Lease, Liability

(3,296,490)

(399,211)

350,391

204,686

Finance Lease, Liability, Payment, Due [Abstract]

70,370

^[1]

9,306

32,232

49,343

^[2]

31,972

9,971

32,170

10,166

2028

118,232

^[1]

10,364

1,342,174

1,352,647

1,627,150

1,441,797

(1,209,189)

(1,192,462)

417,961

249,335

Finance Lease, Liability, Payment, Due [Abstract]

$ 163,100

Lessee purchase option reasonably certain of exercising

105,300

The Skylyne

Lessee purchase option reasonably certain of exercising

$ 38,700

[1]	Finance lease payments in 2024 and 2028 include approximately $38.7 million and $105.3 million, respectively, related to purchase options that the Company was reasonably certain it would exercise upon execution of the ground leases. There can be no assurance that the Company will ultimately exercise the purchase options on the schedule currently contemplated or at all.
[2]	Finance lease payments in 2024 include approximately $38.7 million related to a purchase option that the Company was reasonably certain it would exercise upon execution of the ground lease. There can be no assurance that the Company will ultimately exercise the purchase options on the schedule currently contemplated.

Derivative Instruments and Hedging Activities (Tables)

12 Months Ended

Dec. 31, 2023

Derivative Instruments and Hedging Activities Disclosure [Abstract]

Schedule of Interest Rate Derivatives

BPLP’s and SMBP LLC’s interest rate swap contracts consisted of the following at December 31, 2023 (dollars in thousands):


Derivative Instrument	Aggregate Notional Amount				Strike Rate Range					Balance Sheet Location
			Effective Date	Maturity Date	Low			High			Fair Value
BPLP:
Interest Rate Swaps	$	1,200,000	May 4, 2023	May 16, 2024	4.638	%	—	4.646	%	Prepaid expenses and other assets	$	2,548
Interest Rate Swaps	600,000		December 15, 2023	October 26, 2028	3.790	%	—	3.798	%	Other liabilities	(7,198)
	1,800,000										(4,650)
SMBP LLC
Interest Rate Swaps	300,000		December 14, 2023	April 1, 2025	2.661	%	—	2.688	%	Prepaid expenses and other assets	6,626
	$	2,100,000									$	1,976

Derivative Instruments, Gain (Loss)


	Year ended December 31,
		2023		2022		2021
Amount of gain (loss) related to the effective portion recognized in other comprehensive income (1)		$	(14,405)	$	19,396	$	8,544
Amount of gain (loss) related to the effective portion subsequently reclassified to earnings (2)		$	6,703	$	6,707	$	6,704
Amount of gain (loss) relate do the ineffective portion and amount excluded from effectiveness testing		$	—	$	—	$	—

_______________

(1)Includes the Company’s share of gain (loss) related to the effective portion of derivatives outstanding at its unconsolidated joint venture properties.

(2)Consists of amounts from previous interest rate programs.

Stock Option Rollforward Table (Details) - $ / shares	12 Months Ended
Stock Option Rollforward Table (Details) - $ / shares	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Text Block [Abstract]
Beginning outstanding, shares	103,641	103,641	351,561
Options exercised	0	0	(247,920)
Stock Issued During Period, Shares, Share-based Compensation, Forfeited	(103,641)
Ending outstanding, shares	0	103,641	103,641
Beginning outstanding, Weighted-average Exercise Price	$ 97.01	$ 97.01	$ 96.97
Weighted Average Exercise Price	0	0	96.95
Ending outstanding, Weighted-average Exercise Price	$ 0	$ 97.01	$ 97.01

Summary Of Significant Accounting Policies (Narrative) (Details)

12 Months Ended

Dec. 31, 2023

USD ($)

Dec. 31, 2022

USD ($)

Dec. 31, 2021

USD ($)

Summary Of Significant Accounting Policies [Line Items]

Interest capitalized

$ 42,633,000

$ 52,130,000

$ 53,097,000

Salaries And Related Costs Capitalized

16,100,000

13,700,000

Cash FDIC Insured Limit

250,000

Separate Unrestricted Cash For Deferred Compensation Plan.

36,100,000

32,300,000

Gains (losses) from investments in securities

$ 5,556,000

(6,453,000)

5,626,000

Accounts Receivable, Collection Period Expected

$ 99,100,000

108,000,000

104,300,000

REIT Distribution Requirement

$ 19,200,000

9,100,000

4,200,000

90.00%

Company's Taxable Income Distribution

100.00%

$ 239,000

(150,000)

Prepaid Expense and Other Assets

79,000

64,230,000

43,589,000

Carrying Amount [Member]

Summary Of Significant Accounting Policies [Line Items]

^[1]

302,746,000

Summary Of Significant Accounting Policies [Line Items]

28,700,000

62,900,000

17,200,000

800,000

400,000

Unconsolidated Joint Ventures [Member] | Dock 72 [Member]

$ (272,603,000)

^[2]

(50,705,000)

^[2]

$ 0

Summary Of Significant Accounting Policies [Line Items]

Summary Of Significant Accounting Policies [Line Items]

50,700,000

Interest Rate Cap

$ 600,000,000

Environmental Focused Investment Fund

79,000

Summary Of Significant Accounting Policies [Line Items]

Prepaid Expense and Other Assets

200,000

(200,000)

$ 4,600,000

2,400,000

US Treasury Bill Securities

Summary Of Significant Accounting Policies [Line Items]

U.S. Treasury Bill, Term of Contract

3 months

Cash Equivalents, at Carrying Value

$ 0

Unconsolidated Properties | Platform Sixteen, Three Six Zero Park Avenue South, Two Zero Zero Fifth Avenue and Safeco Plaza

$ 302,700,000

Summary Of Significant Accounting Policies [Line Items]

Number of real estate properties

Unconsolidated Properties | Unconsolidated Joint Ventures [Member]

Summary Of Significant Accounting Policies [Line Items]

Noncontrolling Interest [Line Items]

$ 272,600,000

[1]

Per the guidance in ASC 326, the Company concluded that the risk of nonpayment is nonexistent because the U.S. Government has a long history with no credit losses and therefore, no credit loss allowance was recorded.

[2]

Noncontrolling Interests (Tables)

12 Months Ended

Dec. 31, 2023

Distribution Declared to OP, LTIP, OPP and MYLTIP Units [Table Text Block]

The following table presents BXP’s dividends per share and BPLP’s distributions per OP Unit and LTIP Unit paid or declared during the years ended December 31, 2023, 2022 and 2021:


Record Date	Payment Date	Dividend (Per Share)	Distribution (Per Unit)
December 29, 2023	January 30, 2024	$0.98	$0.98
September 29, 2023	October 31, 2023	$0.98	$0.98
June 30, 2023	July 31, 2023	$0.98	$0.98
March 31, 2023	April 28, 2023	$0.98	$0.98
December 30, 2022	January 30, 2023	$0.98	$0.98
September 30, 2022	October 31, 2022	$0.98	$0.98
June 30, 2022	July 29, 2022	$0.98	$0.98
March 31, 2022	April 29, 2022	$0.98	$0.98
December 31, 2021	January 28, 2022	$0.98	$0.98
September 30, 2021	October 29, 2021	$0.98	$0.98
June 30, 2021	July 30, 2021	$0.98	$0.98
March 31, 2021	April 30, 2021	$0.98	$0.98
December 31, 2020	January 28, 2021	$0.98	$0.98

Noncontrolling Interests [Member]

Noncontrolling Interest [Line Items]

Distribution Declared to OP, LTIP, OPP and MYLTIP Units [Table Text Block]

The following table presents BPLP’s distributions on the OP Units and LTIP Units (including the 2012 OPP Units, 2013 - 2019 MYLTIP Units and, after the February 3, 2023 measurement date, the 2020 MYLTIP Units) and its distributions on the 2020 MYLTIP Units (prior to the February 3, 2023 measurement date) and 2021 - 2023 MYLTIP Units (after the February 7, 2023 issuance date of the 2023 MYLTIP Units) that occurred during the year ended December 31, 2023:


Record Date	Payment Date	Distributions per OP Unit and LTIP Unit	Distributions per MYLTIP Unit
December 29, 2023	January 30, 2024	$0.98	$0.098
September 29, 2023	October 31, 2023	$0.98	$0.098
June 30, 2023	July 31, 2023	$0.98	$0.098
March 31, 2023	April 28, 2023	$0.98	$0.098




December 30, 2022	January 30, 2023	$0.98	$0.098

The following table presents BPLP’s distributions on the OP Units and LTIP Units (including the 2012 OPP Units, 2013 - 2018 MYLTIP Units and, after the February 4, 2022 measurement date, the 2019 MYLTIP Units) and its distributions on the 2019 MYLTIP Units (prior to the February 4, 2022 measurement date) and 2020 - 2022 MYLTIP Units (after the February 1, 2022 issuance date of the 2022 MYLTIP Units) that occurred during the year ended December 31, 2022:


Record Date	Payment Date	Distributions per OP Unit and LTIP Unit	Distributions per MYLTIP Unit
December 30, 2022	January 30, 2023	$0.98	$0.098
September 30, 2022	October 31, 2022	$0.98	$0.098
June 30, 2022	July 29, 2022	$0.98	$0.098
March 31, 2022	April 29, 2022	$0.98	$0.098
December 31, 2021	January 28, 2022	$0.98	$0.098

The following table presents BPLP’s distributions on the OP Units and LTIP Units (including the 2012 OPP Units, 2013 - 2017 MYLTIP Units and, after the February 5, 2021 measurement date, the 2018 MYLTIP Units) and its distributions on the 2018 MYLTIP Units (prior to the February 5, 2021 measurement date) and 2019 - 2021 MYLTIP Units (after the February 2, 2021 issuance date of the 2021 MYLTIP Units) that occurred during the year ended December 31, 2021:


Record Date	Payment Date	Distributions per OP Unit and LTIP Unit	Distributions per MYLTIP Unit
December 31, 2021	January 28, 2022	$0.98	$0.098
September 30, 2021	October 29, 2021	$0.98	$0.098
June 30, 2021	July 30, 2021	$0.98	$0.098
March 31, 2021	April 30, 2021	$0.98	$0.098
December 31, 2020	January 28, 2021	$0.98	$0.098

Unsecured Senior Notes (Narrative) (Details) - USD ($)
$ in Thousands

12 Months Ended

Sep. 01, 2023

May 15, 2023

Dec. 31, 2023

Dec. 31, 2022

Dec. 31, 2021

Proceeds from unsecured senior notes

$ 747,727

$ 749,557

$ 1,695,996

500,000

1,841,500

Proceeds from unsecured senior notes

747,727

749,557

1,695,996

Senior Notes | Boston Properties Limited Partnership

500,000

$ 0

$ 1,841,500

Debt Instrument, Covenant Description

$ 10,550,000

Leverage ratio

60.00%

Secured debt leverage ratio - maximum

50.00%

Interest Coverage - Minimum

1.50

Unencumbered Asset Value - Minimum

150.00%

Debt Instrument, Covenant Compliance

At December 31, 2023, BPLP was in compliance with each of these financial restrictions and requirements.

6.619% unsecured senior notes | Senior Notes | Boston Properties Limited Partnership

$ 750,000

Debt Instrument, Interest Rate, Effective Percentage

6.50%

Senior Notes Pricing

99.697%

6.619%

^[1]

Proceeds from unsecured senior notes

$ 741,300

3.279% unsecured senior notes | Senior Notes | Boston Properties Limited Partnership

$ 500,000

3.125%

Debt Instrument, Increase, Accrued Interest

$ 507,800

$ 7,800

[1]	Yield on issuance date including the effects of discounts on the notes, settlements of interest rate contracts and the amortization of financing costs.

(Common Units) (Narrative) (Details) $ / shares in Units, $ in Thousands						12 Months Ended
	Feb. 07, 2023 USD ($)	Feb. 03, 2023 USD ($) shares	Feb. 04, 2022 USD ($) shares	Dec. 14, 2021 USD ($) shares	Feb. 05, 2021 USD ($) shares	Dec. 31, 2023 USD ($) yr shares	Dec. 31, 2022 USD ($) shares	Dec. 31, 2021 USD ($)	Dec. 29, 2023 $ / shares
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Vesting Period						4 years
Issuance of operating partnership units \| $						$ 0	$ 0	$ 99,689
360 Park South Avenue
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Issuance of operating partnership units \| $				$ 99,700
Boston Properties Limited Partnership
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Redeemable Noncontrolling Interest, Equity, Preferred, Carrying Amount \| $						1,347,575	1,280,886
Issuance of operating partnership units \| $						$ 0	$ 0	99,689
Boston Properties Limited Partnership \| 360 Park South Avenue
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Noncash or Part Noncash Acquisition, Noncash Financial or Equity Instrument Consideration, Shares Issued \| shares				866,503
MYLTIP \| Boston Properties Limited Partnership
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Vesting Period						3 years
Unvested MYLTIP Units [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
unvested MYLTIP distributions as compared to total distributions (percentage)						10.00%
MYLTIP 2021 \| Boston Properties Limited Partnership
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Noncontrolling Interest, Outstanding \| shares						349,267
MYLTIP 2020 [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Final awards percentage of target		50.00%
Value of MYLTIP Awards \| $		$ 3,800
Forfeitures, in units \| shares		152,460
MYLTIP 2022 \| Boston Properties Limited Partnership
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Noncontrolling Interest, Outstanding \| shares						252,151
MYLTIP 2023
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Vesting Period	3 years
Value of MYLTIP Awards \| $	$ 13,100
MYLTIP 2023 \| Boston Properties Limited Partnership
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Noncontrolling Interest, Outstanding \| shares						322,053
MYLTIP 2018
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Final awards percentage of target					29.20%
Value of MYLTIP Awards \| $					$ 4,600
Forfeitures, in units \| shares					285,925
MYLTIP 2019 [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Final awards percentage of target			69.00%
Value of MYLTIP Awards \| $			$ 8,600
Forfeitures, in units \| shares			144,043
OP Units [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
OP Units for redemption (in shares) \| shares						102,699	182,929
Restriction on redemption of OP Unit to Common Stock (in years) \| yr						1
Redemption of OP Unit equivalent to Common Stock (in shares) \| shares						1
Redeemable Noncontrolling Interest, Equity, Preferred, Carrying Amount \| $						$ 1,300,000
Closing price of common stock (in dollars per share) \| $ / shares									$ 70.17
Noncontrolling Interest [Member]
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
Issuance of operating partnership units \| $								$ 99,689
Vested 2012 OPP units and MYLTIPS
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Effects of Changes, Net [Line Items]
OP Units for redemption (in shares) \| shares						94,863	78,249

Deferred Charges (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Goodwill and Intangible Assets Disclosure [Abstract]
Leasing costs, including lease related intangibles	$ 1,168,940	$ 1,095,231
Financing costs	20,600	19,311
Deferred Costs Gross	1,189,540	1,114,542
Less: Accumulated amortization	(429,119)	(381,260)
Deferred Costs, total	$ 760,421	$ 733,282

Real Estate

12 Months Ended

Dec. 31, 2023

Real Estate [Abstract]

Real Estate

3. Real Estate

BXP

Real estate consisted of the following at December 31, 2023 and December 31, 2022 (in thousands):


	December 31, 2023		December 31, 2022
Land	$	5,251,224	$	5,189,811
Right of use assets - finance leases (1)	401,680		237,510
Right of use assets - operating leases (1)	324,298		167,351
Land held for future development (2)	697,061		721,501
Buildings and improvements	16,607,756		15,820,724
Tenant improvements	3,592,172		3,200,743
Furniture, fixtures and equipment	53,716		50,310
Construction in progress	547,280		406,574
Total	27,475,187		25,794,524
Less: Accumulated depreciation	(6,881,728)		(6,298,082)
	$	20,593,459	$	19,496,442

_______________

(1)See Note 4.

(2)Includes pre-development costs.

BPLP

Real estate consisted of the following at December 31, 2023 and December 31, 2022 (in thousands):


	December 31, 2023		December 31, 2022
Land	$	5,156,515	$	5,095,102
Right of use assets - finance leases (1)	401,680		237,510
Right of use assets - operating leases (1)	324,298		167,351
Land held for future development (2)	697,061		721,501
Buildings and improvements	16,336,200		15,547,919
Tenant improvements	3,592,172		3,200,743
Furniture, fixtures and equipment	53,716		50,310
Construction in progress	547,280		406,574
Total	27,108,922		25,427,010
Less: Accumulated depreciation	(6,758,361)		(6,180,474)
	$	20,350,561	$	19,246,536

_______________

(1)See Note 4.

(2)Includes pre-development costs.

Acquisition

On December 14, 2023, the Company completed the acquisition of its joint venture partner’s 45% interest in the joint venture entity that owns Santa Monica Business Park located in Santa Monica, California (See Note 6). Santa Monica Business Park is a 47-acre office park consisting of 21 buildings totaling approximately 1.2 million net rentable square feet. Approximately 70% of the rentable square footage is subject to a ground lease with 75 years remaining, including renewal periods (See Note 4). The property is subject to existing mortgage indebtedness of $300.0 million (See Note 7). The acquisition was completed for a gross purchase price of $38.0 million and the Company acquired net working capital, including cash and cash equivalents of approximately $20 million. The purchase of the joint venture partner’s interest was at a discount and therefore the net assets were recorded at the Company’s relative fair value. Prior to consolidation, the Company had an approximately $149.9 million investment in the joint venture. As the purchase was at a discount, the gain on consolidation was calculated based on the Company’s share of the determined fair market value of the net acquired assets. This resulted in the Company recording a gain upon consolidation of approximately $29.9 million, which is included within income (loss) from

unconsolidated joint ventures in the Consolidated Statement of Operations. The total equity acquired was equal to the Company’s share of the calculated fair market value, used in the gain on consolidation calculation, plus the cash consideration paid. The difference between the determined fair market value and recorded equity is adjusted based on the relative fair value and used to calculate the net assets that were recorded.

The following table summarizes the allocation of the relative fair value of the net assets the Company received at the date of acquisition for Santa Monica Business Park (in thousands):


Land and site improvements	$	46,360
Building and improvements	390,305
Tenant improvements	20,116
In-place lease intangibles	74,022
Above-market lease intangibles	6,715
Below-market lease intangibles	(4,630)
Ground lease intangible	(46,659)
Mortgage note payable adjustment	4,491
Net assets acquired	$	490,720

The following table summarizes the estimated annual amortization of the acquired in-place lease intangibles, acquired ground lease intangible and the acquired above- and below-market lease intangibles for Santa Monica Business Park for each of the five succeeding fiscal years (in thousands):


	Acquired In-Place Lease Intangibles		Acquired Ground Lease Intangible		Acquired Above-Market Lease Intangibles		Acquired Below-Market Lease Intangible
2024	$	32,362	$	10,979	$	3,584	$	1,109
2025	20,782		10,979		1,491		944
2026	7,986		10,979		593		910
2027	4,078		10,979		354		910
2028	2,726		2,193		216		553

The following table summarizes the weighted-average useful life of the acquired in-place lease intangibles, acquired ground lease intangible and the acquired above- and below-market lease intangibles for Santa Monica Business Park as of the acquisition (in years):


	Acquired In-Place Lease Intangibles	Acquired Ground Lease Intangible	Acquired Above-Market Lease Intangibles	Acquired Below-Market Lease Intangible
Weighted-average useful life	2.9	4.2	2.3	5.1

Santa Monica Business Park contributed approximately $3.9 million of revenue and $(0.9) million of net income to the Company for the period December 14, 2023 through December 31, 2023.

Developments/Redevelopments

On January 5, 2023, the Company commenced the development of 290 Binney Street, an approximately 566,000 net rentable square foot laboratory/life sciences project in Cambridge, Massachusetts. Concurrently with the commencement of this project, the Kendall Center Blue Parking Garage was taken out of service and demolished to support the development of this project. 290 Binney Street is 100% pre-leased to AstraZeneca. There can be no assurance that the Company will complete development of the project on the terms and schedule currently contemplated or at all.

On January 30, 2023, the Company commenced the redevelopment of 300 Binney Street at Kendall Center in Cambridge, Massachusetts. 300 Binney Street consisted of an approximately 195,000 net rentable square foot premier workplace that is being redeveloped into approximately 236,000 net rentable square feet of laboratory/life

sciences space. BXP and BPLP recognized approximately $11.0 million of depreciation expense during the year ended December 31, 2023 associated with the acceleration of depreciation on the assets being removed from service and demolished as part of the redevelopment of the property. The project is 100% pre-leased to the Broad Institute. On November 13, 2023, the Company completed the sale of a 45% interest in 300 Binney Street to an institutional investor (See Note 10).

On April 29, 2023, the Company completed and fully placed in-service 2100 Pennsylvania Avenue, a premier workplace project with approximately 476,000 net rentable square feet located in Washington, DC.

On June 1, 2023, the Company completed and fully placed in-service its View Boston observatory at The Prudential Center, a redevelopment of the top three floors of 800 Boylston Street - The Prudential Center, located in Boston, Massachusetts. View Boston observatory at The Prudential Center consists of approximately 63,000 net rentable square feet of retail, including food and beverage, and observation space.

On July 20, 2023, the Company completed and fully placed in-service 140 Kendrick Street - Building A, a premier workplace redevelopment project with approximately 104,000 net rentable square feet located in Needham, Massachusetts. The property is the first net-zero, carbon-neutral office repositioning of its scale in Massachusetts.

On September 26, 2023, the Company partially placed in-service 180 CityPoint, an approximately 329,000 net rentable square feet laboratory/life sciences project located in Waltham, Massachusetts.

On October 5, 2023, the Company partially placed in-service 103 CityPoint, an approximately 113,000 net rentable square feet laboratory/life sciences project located in Waltham, Massachusetts.

On November 30, 2023, the Company elected to suspend redevelopment on 105 Carnegie Center located in Princeton, New Jersey and as a result ceased capitalization on the project. 105 Carnegie Center was a premier workplace that consisted of approximately 70,000 net rentable square feet that was being redeveloped into approximately 73,000 net rentable square feet of laboratory/life sciences space.

SEC Schedule, Article 12-28, Real Estate and Accumulated Depreciation (Details) - USD ($)

12 Months Ended

Dec. 31, 2023

Dec. 31, 2022

Dec. 31, 2021

Dec. 31, 2020

SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]

^[1]

$ 4,166,379,000

5,637,035,000

15,478,086,000

6,306,350,000

^[2]

5,953,798,000

^[3]

20,223,332,000

^[5]

697,061,000

^[4]

$ 721,501,000

547,280,000

406,574,000

27,421,471,000

25,744,214,000

$ 24,108,220,000

$ 23,303,303,000

6,841,404,000

6,260,992,000

5,848,183,000

5,501,637,000

Aggregate cost for tax purpose

53,716,000

50,310,000

25,200,000,000

Real Estate Aggregate Accumulated Depreciation For Tax Purposes

5,900,000,000

Debt Issuance Costs, Net

(33,600,000)

401,680,000

^[6]

237,510,000

^[6]

$ 324,298,000

167,351,000

Maximum [Member]

Real Estate and Accumulated Depreciation, Life Used for Depreciation

40 years

Furniture, fixtures, and equipment

Accumulated Depreciation Related to Furniture, Fixtures and Equipment

$ 40,324,000

Land and Land Improvements [Member]

378,276,000

Buildings and improvements

324,298,000

767Fifth Avenue (the General Motors Building) | Office and Life Sciences Building [Member]

23,404,000

SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]

2,288,004,000

1,796,252,000

1,532,654,000

365,829,000

1,796,252,000

1,898,483,000

3,694,735,000

$ 507,660,000

Prudential Center | Office and Life Sciences Building [Member]

^[7]

(1)

$ 92,077,000

948,357,000

791,280,000

115,634,000

1,687,021,000

29,059,000

1,831,714,000

$ 774,225,000

Embarcadero Center | Office and Life Sciences Building [Member]

^[7]

(1)

$ 179,697,000

847,410,000

524,483,000

195,986,000

1,355,604,000

1,551,590,000

$ 781,405,000

399 Park Avenue | Office and Life Sciences Building [Member]

^[7]

(1)

$ 339,200,000

700,358,000

408,846,000

354,107,000

1,094,297,000

1,448,404,000

$ 482,752,000

601 Lexington Avenue | Office and Life Sciences Building [Member]

^[7]

(1)

SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]

$ 989,181,000

241,600,000

494,782,000

545,612,000

289,639,000

992,355,000

1,281,994,000

$ 372,795,000

Salesforce Tower | Office and Life Sciences Building [Member]

^[7]

(1)

SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]

$ 0

200,349,000

946,205,000

7,623,000

200,349,000

953,828,000

1,154,177,000

$ 159,274,000

200 Clarendon Street and Garage | Office and Life Sciences Building [Member]

^[7]

(1)

$ 219,543,000

667,884,000

251,372,000

250,910,000

887,889,000

1,138,799,000

$ 338,529,000

250 West 55th Street | Office and Life Sciences Building [Member]

^[7]

(1)

$ 285,263,000

603,167,000

52,917,000

285,263,000

656,084,000

941,347,000

$ 198,081,000

100 Federal Street | Office and Life Sciences Building [Member]

^[7]

(1)

$ 131,067,000

435,954,000

127,199,000

131,067,000

563,153,000

694,220,000

$ 172,079,000

Times Square Tower | Office and Life Sciences Building [Member]

^[7]

(1)

$ 165,413,000

380,438,000

140,281,000

169,193,000

516,939,000

686,132,000

$ 256,942,000

Madison Centre | Office and Life Sciences Building [Member]

^[7]

(1)

$ 104,641,000

564,336,000

4,082,000

104,641,000

568,418,000

673,059,000

$ 35,516,000

Carnegie Center | Office and Life Sciences Building [Member]

^[7]

(1)

$ 142,666,000

316,856,000

177,545,000

94,243,000

484,024,000

58,800,000

637,067,000

$ 267,232,000

Santa Monica Business Park [Member] | Office and Life Sciences Building [Member]

^[7]

(1)

SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]

$ 295,649,000

46,360,000

410,421,000

164,229,000

210,471,000

410,535,000

4,000

621,010,000

$ 865,000

Reston Next | Office and Life Sciences Building [Member]

^[7]

(1)

$ 35,549,000

525,277,000

2,901,000

557,925,000

560,826,000

$ 32,504,000

125 Broadway | Office and Life Sciences Building [Member]

^[7]

(1)

$ 126,364,000

433,662,000

4,000,000

126,364,000

437,662,000

564,026,000

$ 20,717,000

Atlantic Wharf | Office and Life Sciences Building [Member]

^[7]

(1)

$ 63,988,000

454,537,000

39,399,000

63,988,000

493,936,000

557,924,000

$ 180,686,000

2100 Pennsylvania Avenue | Office and Life Sciences Building [Member]

^[7]

(1)

$ 185,203,000

324,206,000

185,203,000

324,206,000

509,409,000

$ 20,768,000

599 Lexington Avenue | Office and Life Sciences Building [Member]

^[7]

(1)

$ 81,040,000

100,507,000

258,659,000

87,852,000

352,354,000

440,206,000

$ 197,429,000

Fountain Square | Office and Life Sciences Building [Member]

^[7]

(1)

$ 56,853,000

306,298,000

49,874,000

56,853,000

356,172,000

413,025,000

$ 111,481,000

510 Madison Avenue | Office and Life Sciences Building [Member]

^[7]

(1)

$ 103,000,000

253,665,000

33,100,000

103,000,000

286,765,000

389,765,000

$ 104,052,000

325 Main Street | Office and Life Sciences Building [Member]

^[7]

(1)

SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]

^[8]

$ 0

21,596,000

312,492,000

30,933,000

21,596,000

343,425,000

365,021,000

$ 14,833,000

680 Folsom Street | Office and Life Sciences Building [Member]

^[7]

(1)

$ 72,545,000

219,766,000

8,026,000

72,545,000

227,792,000

300,337,000

$ 80,964,000

145 Broadway | Office and Life Sciences Building [Member]

^[7]

(1)

$ 121,000

273,013,000

26,359,000

23,367,000

276,126,000

299,493,000

$ 35,390,000

2200 Pennsylvania Avenue | Office and Life Sciences Building [Member]

^[7]

(1)

$ 0

183,541,000

114,090,000

102,979,000

194,652,000

297,631,000

$ 77,357,000

South of Market and Democracy Tower | Office and Life Sciences Building [Member]

^[7]

(1)

$ 13,603,000

237,479,000

30,952,000

13,687,000

268,347,000

282,034,000

$ 108,973,000

Bay Colony Corporate Center | Office and Life Sciences Building [Member]

^[7]

(1)

$ 18,789,000

148,451,000

96,639,000

18,789,000

240,416,000

4,674,000

263,879,000

$ 113,123,000

535 Mission Street | Office and Life Sciences Building [Member]

^[7]

(1)

$ 40,933,000

148,378,000

4,629,000

40,934,000

153,006,000

193,940,000

$ 46,615,000

Mountain View Research Park | Office and Life Sciences Building [Member]

^[7]

(1)

$ 95,066,000

68,373,000

21,069,000

95,066,000

89,442,000

184,508,000

$ 33,095,000

Reservoir Place | Office and Life Sciences Building [Member]

^[7]

(1)

$ 18,605,000

104,124,000

56,160,000

20,108,000

156,954,000

1,827,000

178,889,000

$ 90,808,000

140 Kendrick Street | Office and Life Sciences Building [Member]

^[7]

(1)

$ 18,095,000

66,905,000

71,861,000

19,092,000

137,769,000

156,861,000

$ 46,586,000

1330 Connecticut Avenue | Office and Life Sciences Building [Member]

^[7]

(1)

$ 25,982,000

82,311,000

39,924,000

27,135,000

121,082,000

148,217,000

$ 53,332,000

880 Winter Street [Member] | Office and Life Sciences Building [Member]

^[7]

(1)

$ 15,597,000

37,255,000

95,265,000

15,597,000

132,520,000

148,117,000

$ 10,056,000

One Freedom Square | Office and Life Sciences Building [Member]

^[7]

(1)

$ 9,929,000

84,504,000

48,985,000

11,293,000

132,125,000

143,418,000

$ 68,406,000

Two Freedom Square | Office and Life Sciences Building [Member]

^[7]

(1)

$ 13,930,000

77,739,000

45,068,000

15,420,000

121,317,000

136,737,000

$ 44,662,000

Kingstowne Towne Center | Office and Life Sciences Building [Member]

^[7]

(1)

$ 18,021,000

109,038,000

4,665,000

18,062,000

113,662,000

131,724,000

$ 54,480,000

One and Two Reston Overlook | Office and Life Sciences Building [Member]

^[7]

(1)

$ 16,456,000

66,192,000

45,224,000

16,179,000

111,693,000

127,872,000

$ 61,572,000

Shady Grove Innovation District [Member] | Office and Life Sciences Building [Member]

^[7]

(1)

$ 52,030,000

64,212,000

10,676,000

26,834,000

34,954,000

65,130,000

126,918,000

$ 4,701,000

Weston Corporate Center | Office and Life Sciences Building [Member]

^[7]

(1)

$ 25,753,000

92,312,000

1,038,000

25,854,000

93,249,000

119,103,000

$ 41,485,000

355 Main Street | Office and Life Sciences Building [Member]

^[7]

(1)

SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]

$ 593,545,000

18,863,000

53,346,000

41,772,000

21,173,000

92,808,000

113,981,000

$ 36,957,000

17Fifty Presidents Street | Office and Life Sciences Building [Member]

^[7]

(1)

$ 0

113,362,000

162,000

113,524,000

113,524,000

$ 16,624,000

200 West Street | Office and Life Sciences Building [Member]

^[7]

(1)

$ 16,148,000

24,983,000

71,199,000

16,813,000

95,160,000

357,000

112,330,000

$ 28,192,000

Discovery Square | Office and Life Sciences Building [Member]

^[7]

(1)

$ 11,198,000

71,782,000

21,744,000

12,533,000

92,191,000

104,724,000

$ 57,015,000

10 CityPoint | Office and Life Sciences Building [Member]

^[7]

(1)

$ 1,953,000

85,752,000

7,571,000

2,288,000

92,988,000

95,276,000

$ 24,003,000

90 Broadway | Office and Life Sciences Building [Member]

^[7]

(1)

SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]

^[8]

$ 0

19,104,000

52,078,000

22,742,000

20,785,000

73,139,000

93,924,000

$ 31,538,000

Waltham Weston Corporate Center | Office and Life Sciences Building [Member]

^[7]

(1)

$ 10,385,000

60,694,000

20,705,000

11,097,000

80,687,000

91,784,000

$ 45,601,000

153 & 211 Second Avenue [Member] | Office and Life Sciences Building [Member]

^[7]

(1)

$ 33,233,000

55,940,000

718,000

33,233,000

55,940,000

718,000

89,891,000

$ 6,186,000

230 CityPoint | Office and Life Sciences Building [Member]

^[7]

(1)

$ 13,189,000

49,823,000

24,297,000

13,807,000

73,502,000

87,309,000

$ 40,959,000

20 Citypoint | Office and Life Sciences Building [Member]

^[7]

(1)

$ 4,887,000

72,764,000

7,072,000

4,887,000

79,836,000

84,723,000

$ 13,031,000

Sumner Square | Office and Life Sciences Building [Member]

^[7]

(1)

$ 624,000

28,745,000

51,253,000

27,837,000

52,785,000

80,622,000

$ 32,911,000

77 CityPoint | Office and Life Sciences Building [Member]

^[7]

(1)

$ 13,847,000

60,383,000

1,506,000

14,023,000

61,713,000

75,736,000

$ 26,943,000

2440 West El Camino Real | Office and Life Sciences Building [Member]

^[7]

(1)

$ 16,741,000

51,285,000

6,565,000

16,741,000

57,850,000

74,591,000

$ 21,469,000

Wisconsin Place | Office and Life Sciences Building [Member]

^[7]

(1)

$ 0

53,349,000

13,834,000

67,183,000

67,183,000

$ 28,960,000

Reston Corporate Center | Office and Life Sciences Building [Member]

^[7]

(1)

$ 9,135,000

50,857,000

4,489,000

10,148,000

54,333,000

64,481,000

$ 34,194,000

255 Main Street | Office and Life Sciences Building [Member]

^[7]

(1)

$ 134,000

25,110,000

33,330,000

548,000

58,026,000

58,574,000

$ 43,927,000

University Place | Office and Life Sciences Building [Member]

^[7]

(1)

$ 0

37,091,000

15,768,000

4,807,000

48,052,000

52,859,000

$ 37,130,000

890 Winter Street | Office and Life Sciences Building [Member]

^[7]

(1)

$ 13,913,000

28,557,000

8,507,000

13,913,000

37,064,000

50,977,000

$ 7,296,000

Capital Gallery | Office and Life Sciences Building [Member]

^[7]

(1)

$ 4,725,000

29,565,000

10,361,000

8,662,000

35,989,000

44,651,000

$ 23,764,000

North First Business Park | Office and Life Sciences Building [Member]

^[7]

(1)

$ 23,398,000

13,069,000

5,258,000

23,378,000

18,347,000

41,725,000

$ 17,354,000

150 Broadway | Office and Life Sciences Building [Member]

^[7]

(1)

$ 850,000

25,042,000

15,749,000

1,323,000

40,318,000

41,641,000

$ 18,506,000

105 Broadway | Office and Life Sciences Building [Member]

^[7]

(1)

$ 1,299,000

12,943,000

12,723,000

2,395,000

24,570,000

26,965,000

$ 16,847,000

Lexington Office Park | Office and Life Sciences Building [Member]

^[7]

(1)

$ 998,000

1,426,000

19,924,000

1,263,000

19,470,000

1,615,000

22,348,000

$ 17,200,000

The Point | Office and Life Sciences Building [Member]

^[7]

(1)

$ 6,395,000

10,040,000

546,000

6,492,000

10,489,000

16,981,000

$ 2,638,000

690 Folsom Street | Office and Life Sciences Building [Member]

^[7]

(1)

$ 3,219,000

11,038,000

1,877,000

3,219,000

12,915,000

16,134,000

$ 4,280,000

33 Hayden Avenue | Office and Life Sciences Building [Member]

^[7]

(1)

$ 266,000

3,234,000

11,502,000

425,000

14,577,000

15,002,000

$ 9,090,000

The Avant Retail | Office and Life Sciences Building [Member]

^[7]

(1)

$ 1,499,000

6,647,000

2,577,000

1,499,000

9,224,000

10,723,000

$ 3,587,000

92-100 Hayden Avenue | Office and Life Sciences Building [Member]

^[7]

(1)

$ 594,000

6,748,000

1,922,000

778,000

8,486,000

9,264,000

$ 7,388,000

32 Hartwell Avenue | Office and Life Sciences Building [Member]

^[7]

(1)

$ 168,000

1,943,000

6,403,000

314,000

8,200,000

8,514,000

$ 2,931,000

250 Binney Street | Office and Life Sciences Building [Member]

^[7]

(1)

$ 110,000

4,483,000

3,593,000

273,000

7,913,000

8,186,000

$ 7,244,000

453 Ravendale Drive | Office and Life Sciences Building [Member]

^[7]

(1)

$ 5,477,000

1,090,000

1,286,000

5,477,000

2,376,000

7,853,000

$ 1,086,000

17 Hartwell Avenue | Office and Life Sciences Building [Member]

^[7]

(1)

$ 26,000

150,000

6,064,000

65,000

6,175,000

6,240,000

$ 3,755,000

The Skylyne | Residential Building

^[7]

(1)

$ 28,962,000

239,077,000

1,792,000

28,962,000

240,869,000

269,831,000

$ 20,181,000

Signature at Reston | Residential Building

^[7]

(1)

$ 27,076,000

190,580,000

3,817,000

27,076,000

194,397,000

221,473,000

$ 27,876,000

Proto Kendall Square | Residential Building

^[7]

(1)

$ 9,243,000

127,248,000

3,336,000

9,245,000

130,582,000

139,827,000

$ 17,820,000

The Lofts at Atlantic Wharf | Residential Building

^[7]

(1)

$ 3,529,000

54,891,000

2,509,000

3,529,000

57,400,000

60,929,000

$ 18,631,000

Boston Cambridge Marriott | Hotel [Member]

^[7]

(1)

$ 478,000

37,918,000

32,131,000

1,201,000

68,697,000

629,000

70,527,000

$ 53,282,000

Kendall Center Green Garage | Garage

^[7]

(1)

SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]

^[8]

$ 0

35,035,000

7,335,000

103,000

42,267,000

42,370,000

$ 18,414,000

Kendall Center Yellow Garage | Garage

^[7]

(1)

$ 1,256,000

15,697,000

1,743,000

1,434,000

17,262,000

18,696,000

$ 7,857,000

^[7]

(1)

290 Binney | Development

$ 0

243,099,000

1,054,000

242,045,000

$ 243,099,000

180 CityPoint [Member] | Development

N/A

$ 0

214,754,000

10,908,000

108,970,000

94,876,000

214,754,000

$ 541,000

300 Binney Street | Development

N/A

$ 18,080,000

51,262,000

38,454,000

18,080,000

27,805,000

61,911,000

107,796,000

$ 6,719,000

103 CityPoint | Development

N/A

$ 0

88,190,000

4,672,000

3,025,000

8,672,000

71,821,000

88,190,000

$ 18,000

Reston Next Office Phase II | Development

N/A

$ 0

39,201,000

39,201,000

$ 39,201,000

Reston Next Retail | Development

N/A

$ 0

8,367,000

8,367,000

$ 8,367,000

343 Madison Avenue | Land

N/A

$ 0

206,052,000

158,885,000

47,167,000

$ 206,052,000

777 Harrison Street | Land

N/A

$ 144,647,000

28,334,000

47,000

172,934,000

172,981,000

$ 29,000

Back Bay Station Master Plan | Land

N/A

$ 0

78,150,000

78,150,000

$ 78,150,000

3625 - 3635 Peterson Way | Land

N/A

$ 63,206,000

5,173,000

68,379,000

$ 68,379,000

Kendall Center Master Plan | Land

N/A

$ 0

48,857,000

48,857,000

$ 48,857,000

North First Master Plan | Land

N/A

$ 35,004,000

4,068,000

39,072,000

$ 39,072,000

N/A

Plaza at Almaden | Land

$ 0

38,163,000

38,163,000

$ 38,163,000

CityPoint South Master Plan | Land

N/A

$ 0

25,594,000

25,594,000

$ 25,594,000

Springfield Metro Center | Land

N/A

$ 0

19,896,000

19,896,000

$ 19,896,000

Reston Gateway Master Plan | Land

N/A

$ 0

13,908,000

13,908,000

$ 13,908,000

N/A

Weston Quarry | Land

$ 0

1,249,000

1,249,000

$ 1,249,000

Broad Run Business Park | Land

N/A

$ 0

1,186,000

1,186,000

$ 1,186,000

Reston Overlook Master Plan | Land

N/A

$ 0

80,000

80,000

$ 80,000

N/A

SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]

^[9]

$ 4,166,379,000

5,637,035,000

15,478,086,000

5,940,085,000

^[10]

5,859,089,000

^[11]

19,951,776,000

^[5]

697,061,000

^[12]

721,501,000

547,280,000

406,574,000

27,055,206,000

25,376,700,000

23,734,833,000

22,926,494,000

6,718,037,000

6,143,384,000

$ 5,736,240,000

$ 5,396,111,000

Aggregate cost for tax purpose

53,716,000

50,310,000

28,200,000,000

Real Estate Aggregate Accumulated Depreciation For Tax Purposes

6,600,000,000

Debt Issuance Costs, Net

(33,600,000)

401,680,000

^[6]

237,510,000

Boston Properties Limited Partnership | Maximum [Member]

^[6]

$ 324,298,000

$ 167,351,000

Real Estate and Accumulated Depreciation, Life Used for Depreciation

40 years

Boston Properties Limited Partnership | Furniture, fixtures, and equipment

Accumulated Depreciation Related to Furniture, Fixtures and Equipment

$ 40,324,000

Boston Properties Limited Partnership | Land and Land Improvements [Member]

378,276,000

Boston Properties Limited Partnership | Buildings and improvements

324,298,000

Boston Properties Limited Partnership | 767Fifth Avenue (the General Motors Building) | Office and Life Sciences Building [Member]

23,404,000

SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]

2,288,004,000

1,796,252,000

1,532,654,000

365,829,000

1,796,252,000

1,898,483,000

3,694,735,000

$ 507,660,000

Boston Properties Limited Partnership | Prudential Center | Office and Life Sciences Building [Member]

^[13]

(1)

$ 92,077,000

948,357,000

732,224,000

100,535,000

1,643,064,000

29,059,000

1,772,658,000

$ 754,356,000

Boston Properties Limited Partnership | Embarcadero Center | Office and Life Sciences Building [Member]

^[13]

(1)

$ 179,697,000

847,410,000

462,102,000

180,419,000

1,308,790,000

1,489,209,000

$ 760,144,000

Boston Properties Limited Partnership | 399 Park Avenue | Office and Life Sciences Building [Member]

^[13]

(1)

$ 339,200,000

700,358,000

349,238,000

339,200,000

1,049,596,000

1,388,796,000

$ 462,543,000

Boston Properties Limited Partnership | 601 Lexington Avenue | Office and Life Sciences Building [Member]

^[13]

(1)

SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]

$ 989,181,000

241,600,000

494,782,000

508,526,000

279,281,000

965,627,000

1,244,908,000

$ 360,656,000

Boston Properties Limited Partnership | Salesforce Tower | Office and Life Sciences Building [Member]

^[13]

(1)

$ 200,349,000

946,205,000

7,623,000

200,349,000

953,828,000

1,154,177,000

$ 159,274,000

Boston Properties Limited Partnership | 200 Clarendon Street and Garage | Office and Life Sciences Building [Member]

^[13]

(1)

$ 219,543,000

667,884,000

251,372,000

250,910,000

887,889,000

1,138,799,000

$ 338,529,000

Boston Properties Limited Partnership | 250 West 55th Street | Office and Life Sciences Building [Member]

^[13]

(1)

$ 285,263,000

603,167,000

52,917,000

285,263,000

656,084,000

941,347,000

$ 198,081,000

Boston Properties Limited Partnership | 100 Federal Street | Office and Life Sciences Building [Member]

^[13]

(1)

$ 131,067,000

435,954,000

127,199,000

131,067,000

563,153,000

694,220,000

$ 172,079,000

Boston Properties Limited Partnership | Times Square Tower | Office and Life Sciences Building [Member]

^[13]

(1)

$ 165,413,000

380,438,000

102,302,000

159,694,000

488,459,000

648,153,000

$ 244,067,000

Boston Properties Limited Partnership | Madison Centre | Office and Life Sciences Building [Member]

^[13]

(1)

$ 104,641,000

564,336,000

4,082,000

104,641,000

568,418,000

673,059,000

$ 35,516,000

Boston Properties Limited Partnership | Carnegie Center | Office and Life Sciences Building [Member]

^[13]

(1)

$ 142,666,000

316,856,000

162,582,000

90,501,000

472,803,000

58,800,000

622,104,000

$ 262,096,000

Boston Properties Limited Partnership | Santa Monica Business Park [Member] | Office and Life Sciences Building [Member]

^[13]

(1)

SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]

$ 295,649,000

46,360,000

410,421,000

164,229,000

210,471,000

410,535,000

4,000

621,010,000

$ 865,000

Boston Properties Limited Partnership | Reston Next | Office and Life Sciences Building [Member]

^[13]

(1)

$ 35,549,000

525,277,000

2,901,000

557,925,000

560,826,000

$ 32,504,000

Boston Properties Limited Partnership | 125 Broadway | Office and Life Sciences Building [Member]

^[13]

(1)

$ 126,364,000

433,662,000

4,000,000

126,364,000

437,662,000

564,026,000

$ 20,717,000

Boston Properties Limited Partnership | Atlantic Wharf | Office and Life Sciences Building [Member]

^[13]

(1)

$ 63,988,000

454,537,000

39,399,000

63,988,000

493,936,000

557,924,000

$ 180,686,000

Boston Properties Limited Partnership | 2100 Pennsylvania Avenue | Office and Life Sciences Building [Member]

^[13]

(1)

$ 185,203,000

324,206,000

185,203,000

324,206,000

509,409,000

$ 20,768,000

Boston Properties Limited Partnership | 599 Lexington Avenue | Office and Life Sciences Building [Member]

^[13]

(1)

$ 81,040,000

100,507,000

231,417,000

81,040,000

331,924,000

412,964,000

$ 188,193,000

Boston Properties Limited Partnership | Fountain Square | Office and Life Sciences Building [Member]

^[13]

(1)

$ 56,853,000

306,298,000

49,874,000

56,853,000

356,172,000

413,025,000

$ 111,481,000

Boston Properties Limited Partnership | 510 Madison Avenue | Office and Life Sciences Building [Member]

^[13]

(1)

$ 103,000,000

253,665,000

33,100,000

103,000,000

286,765,000

389,765,000

$ 104,052,000

Boston Properties Limited Partnership | 325 Main Street | Office and Life Sciences Building [Member]

^[13]

(1)

SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]

^[14]

$ 0

21,596,000

312,492,000

30,740,000

21,403,000

343,425,000

364,828,000

$ 14,833,000

Boston Properties Limited Partnership | 680 Folsom Street | Office and Life Sciences Building [Member]

^[13]

(1)

$ 72,545,000

219,766,000

8,026,000

72,545,000

227,792,000

300,337,000

$ 80,964,000

Boston Properties Limited Partnership | 145 Broadway | Office and Life Sciences Building [Member]

^[13]

(1)

$ 121,000

273,013,000

26,156,000

23,164,000

276,126,000

299,290,000

$ 35,390,000

Boston Properties Limited Partnership | 2200 Pennsylvania Avenue | Office and Life Sciences Building [Member]

^[13]

(1)

$ 0

183,541,000

114,090,000

102,979,000

194,652,000

297,631,000

$ 77,357,000

Boston Properties Limited Partnership | South of Market and Democracy Tower | Office and Life Sciences Building [Member]

^[13]

(1)

$ 13,603,000

237,479,000

30,616,000

13,603,000

268,095,000

281,698,000

$ 108,875,000

Boston Properties Limited Partnership | Bay Colony Corporate Center | Office and Life Sciences Building [Member]

^[13]

(1)

$ 18,789,000

148,451,000

96,639,000

18,789,000

240,416,000

4,674,000

263,879,000

$ 113,123,000

Boston Properties Limited Partnership | 535 Mission Street | Office and Life Sciences Building [Member]

^[13]

(1)

$ 40,933,000

148,378,000

4,629,000

40,934,000

153,006,000

193,940,000

$ 46,615,000

Boston Properties Limited Partnership | Mountain View Research Park | Office and Life Sciences Building [Member]

^[13]

(1)

$ 95,066,000

68,373,000

21,069,000

95,066,000

89,442,000

184,508,000

$ 33,095,000

Boston Properties Limited Partnership | Reservoir Place | Office and Life Sciences Building [Member]

^[13]

(1)

$ 18,605,000

104,124,000

52,085,000

19,089,000

153,898,000

1,827,000

174,814,000

$ 89,426,000

Boston Properties Limited Partnership | 140 Kendrick Street | Office and Life Sciences Building [Member]

^[13]

(1)

$ 18,095,000

66,905,000

67,871,000

18,095,000

134,776,000

152,871,000

$ 45,233,000

Boston Properties Limited Partnership | 1330 Connecticut Avenue | Office and Life Sciences Building [Member]

^[13]

(1)

$ 25,982,000

82,311,000

35,311,000

25,982,000

117,622,000

143,604,000

$ 51,767,000

Boston Properties Limited Partnership | 880 Winter Street [Member] | Office and Life Sciences Building [Member]

^[13]

(1)

$ 15,597,000

37,255,000

95,265,000

15,597,000

132,520,000

148,117,000

$ 10,056,000

Boston Properties Limited Partnership | One Freedom Square | Office and Life Sciences Building [Member]

^[13]

(1)

$ 9,929,000

84,504,000

43,348,000

9,883,000

127,898,000

137,781,000

$ 66,495,000

Boston Properties Limited Partnership | Two Freedom Square | Office and Life Sciences Building [Member]

^[13]

(1)

$ 13,930,000

77,739,000

38,856,000

13,866,000

116,659,000

130,525,000

$ 42,556,000

Boston Properties Limited Partnership | Kingstowne Towne Center | Office and Life Sciences Building [Member]

^[13]

(1)

$ 18,021,000

109,038,000

4,501,000

18,021,000

113,539,000

131,560,000

$ 54,432,000

Boston Properties Limited Partnership | One and Two Reston Overlook | Office and Life Sciences Building [Member]

^[13]

(1)

$ 16,456,000

66,192,000

40,806,000

15,074,000

108,380,000

123,454,000

$ 60,074,000

Boston Properties Limited Partnership | Shady Grove Innovation District [Member] | Office and Life Sciences Building [Member]

^[13]

(1)

$ 52,030,000

64,212,000

10,676,000

26,834,000

34,954,000

65,130,000

126,918,000

$ 4,701,000

Boston Properties Limited Partnership | Weston Corporate Center | Office and Life Sciences Building [Member]

^[13]

(1)

$ 25,753,000

92,312,000

1,038,000

25,854,000

93,249,000

119,103,000

$ 41,485,000

Boston Properties Limited Partnership | 355 Main Street | Office and Life Sciences Building [Member]

^[13]

(1)

SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]

$ 593,545,000

18,863,000

53,346,000

41,474,000

21,098,000

92,585,000

113,683,000

$ 36,858,000

Boston Properties Limited Partnership | 17Fifty Presidents Street | Office and Life Sciences Building [Member]

^[13]

(1)

$ 0

113,362,000

162,000

113,524,000

113,524,000

$ 16,624,000

Boston Properties Limited Partnership | 200 West Street | Office and Life Sciences Building [Member]

^[13]

(1)

$ 16,148,000

24,983,000

68,538,000

16,148,000

93,164,000

357,000

109,669,000

$ 27,290,000

Boston Properties Limited Partnership | Discovery Square | Office and Life Sciences Building [Member]

^[13]

(1)

$ 11,198,000

71,782,000

16,199,000

11,146,000

88,033,000

99,179,000

$ 55,135,000

Boston Properties Limited Partnership | 10 CityPoint | Office and Life Sciences Building [Member]

^[13]

(1)

$ 1,953,000

85,752,000

7,410,000

2,127,000

92,988,000

95,115,000

$ 24,003,000

Boston Properties Limited Partnership | 90 Broadway | Office and Life Sciences Building [Member]

^[13]

(1)

SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]

^[14]

$ 0

19,104,000

52,078,000

22,563,000

20,741,000

73,004,000

93,745,000

$ 31,484,000

Boston Properties Limited Partnership | Waltham Weston Corporate Center | Office and Life Sciences Building [Member]

^[13]

(1)

$ 10,385,000

60,694,000

17,718,000

10,350,000

78,447,000

88,797,000

$ 44,588,000

Boston Properties Limited Partnership | 153 & 211 Second Avenue [Member] | Office and Life Sciences Building [Member]

^[13]

(1)

$ 33,233,000

55,940,000

718,000

33,233,000

55,940,000

718,000

89,891,000

$ 6,186,000

Boston Properties Limited Partnership | 230 CityPoint | Office and Life Sciences Building [Member]

^[13]

(1)

$ 13,189,000

49,823,000

22,680,000

13,403,000

72,289,000

85,692,000

$ 40,413,000

Boston Properties Limited Partnership | 20 Citypoint | Office and Life Sciences Building [Member]

^[13]

(1)

$ 4,887,000

72,764,000

7,072,000

4,887,000

79,836,000

84,723,000

$ 13,031,000

Boston Properties Limited Partnership | Sumner Square | Office and Life Sciences Building [Member]

^[13]

(1)

$ 624,000

28,745,000

49,173,000

27,317,000

51,225,000

78,542,000

$ 32,209,000

Boston Properties Limited Partnership | 77 CityPoint | Office and Life Sciences Building [Member]

^[13]

(1)

$ 13,847,000

60,383,000

1,401,000

13,997,000

61,634,000

75,631,000

$ 26,911,000

Boston Properties Limited Partnership | 2440 West El Camino Real | Office and Life Sciences Building [Member]

^[13]

(1)

$ 16,741,000

51,285,000

6,565,000

16,741,000

57,850,000

74,591,000

$ 21,469,000

Boston Properties Limited Partnership | Wisconsin Place | Office and Life Sciences Building [Member]

^[13]

(1)

$ 0

53,349,000

13,834,000

67,183,000

67,183,000

$ 28,960,000

Boston Properties Limited Partnership | Reston Corporate Center | Office and Life Sciences Building [Member]

^[13]

(1)

$ 9,135,000

50,857,000

1,878,000

9,496,000

52,374,000

61,870,000

$ 33,309,000

Boston Properties Limited Partnership | 255 Main Street | Office and Life Sciences Building [Member]

^[13]

(1)

$ 134,000

25,110,000

31,674,000

134,000

56,784,000

56,918,000

$ 43,368,000

Boston Properties Limited Partnership | University Place | Office and Life Sciences Building [Member]

^[13]

(1)

$ 0

37,091,000

14,318,000

4,807,000

46,602,000

51,409,000

$ 36,037,000

Boston Properties Limited Partnership | 890 Winter Street | Office and Life Sciences Building [Member]

^[13]

(1)

$ 13,913,000

28,557,000

8,507,000

13,913,000

37,064,000

50,977,000

$ 7,296,000

Boston Properties Limited Partnership | Capital Gallery | Office and Life Sciences Building [Member]

^[13]

(1)

$ 4,725,000

29,565,000

5,698,000

6,128,000

33,860,000

39,988,000

$ 22,801,000

Boston Properties Limited Partnership | North First Business Park | Office and Life Sciences Building [Member]

^[13]

(1)

$ 23,398,000

13,069,000

5,235,000

23,372,000

18,330,000

41,702,000

$ 17,347,000

Boston Properties Limited Partnership | 150 Broadway | Office and Life Sciences Building [Member]

^[13]

(1)

$ 850,000

25,042,000

13,744,000

822,000

38,814,000

39,636,000

$ 17,823,000

Boston Properties Limited Partnership | 105 Broadway | Office and Life Sciences Building [Member]

^[13]

(1)

$ 1,299,000

12,943,000

10,617,000

1,868,000

22,991,000

24,859,000

$ 16,133,000

Boston Properties Limited Partnership | Lexington Office Park | Office and Life Sciences Building [Member]

^[13]

(1)

$ 998,000

1,426,000

19,160,000

1,072,000

18,897,000

1,615,000

21,584,000

$ 16,945,000

Boston Properties Limited Partnership | The Point | Office and Life Sciences Building [Member]

^[13]

(1)

$ 6,395,000

10,040,000

546,000

6,492,000

10,489,000

16,981,000

$ 2,638,000

Boston Properties Limited Partnership | 690 Folsom Street | Office and Life Sciences Building [Member]

^[13]

(1)

$ 3,219,000

11,038,000

1,877,000

3,219,000

12,915,000

16,134,000

$ 4,280,000

Boston Properties Limited Partnership | 33 Hayden Avenue | Office and Life Sciences Building [Member]

^[13]

(1)

$ 266,000

3,234,000

10,865,000

266,000

14,099,000

14,365,000

$ 8,873,000

Boston Properties Limited Partnership | The Avant Retail | Office and Life Sciences Building [Member]

^[13]

(1)

$ 1,499,000

6,647,000

2,577,000

1,499,000

9,224,000

10,723,000

$ 3,587,000

Boston Properties Limited Partnership | 92-100 Hayden Avenue | Office and Life Sciences Building [Member]

^[13]

(1)

$ 594,000

6,748,000

1,193,000

595,000

7,940,000

8,535,000

$ 7,140,000

Boston Properties Limited Partnership | 32 Hartwell Avenue | Office and Life Sciences Building [Member]

^[13]

(1)

$ 168,000

1,943,000

5,817,000

168,000

7,760,000

7,928,000

$ 2,731,000

Boston Properties Limited Partnership | 250 Binney Street | Office and Life Sciences Building [Member]

^[13]

(1)

$ 110,000

4,483,000

2,939,000

110,000

7,422,000

7,532,000

$ 7,026,000

Boston Properties Limited Partnership | 453 Ravendale Drive | Office and Life Sciences Building [Member]

^[13]

(1)

$ 5,477,000

1,090,000

1,286,000

5,477,000

2,376,000

7,853,000

$ 1,086,000

Boston Properties Limited Partnership | 17 Hartwell Avenue | Office and Life Sciences Building [Member]

^[13]

(1)

$ 26,000

150,000

5,907,000

26,000

6,057,000

6,083,000

$ 3,701,000

Boston Properties Limited Partnership | The Skylyne | Residential Building

^[13]

(1)

$ 28,962,000

239,077,000

1,792,000

28,962,000

240,869,000

269,831,000

$ 20,181,000

Boston Properties Limited Partnership | Signature at Reston | Residential Building

^[13]

(1)

$ 27,076,000

190,580,000

3,817,000

27,076,000

194,397,000

221,473,000

$ 27,876,000

Boston Properties Limited Partnership | Proto Kendall Square | Residential Building

^[13]

(1)

$ 9,243,000

127,248,000

3,336,000

9,245,000

130,582,000

139,827,000

$ 17,820,000

Boston Properties Limited Partnership | The Lofts at Atlantic Wharf | Residential Building

^[13]

(1)

$ 3,529,000

54,891,000

2,509,000

3,529,000

57,400,000

60,929,000

$ 18,631,000

Boston Properties Limited Partnership | Boston Cambridge Marriott | Hotel [Member]

^[13]

(1)

$ 478,000

37,918,000

29,240,000

478,000

66,529,000

629,000

67,636,000

$ 52,302,000

Boston Properties Limited Partnership | Kendall Center Green Garage | Garage

^[13]

(1)

SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]

^[14]

$ 0

35,035,000

6,921,000

41,956,000

41,956,000

$ 18,275,000

Boston Properties Limited Partnership | Kendall Center Yellow Garage | Garage

^[13]

(1)

$ 1,256,000

15,697,000

1,031,000

1,256,000

16,728,000

17,984,000

$ 7,619,000

Boston Properties Limited Partnership | 290 Binney | Development

^[13]

(1)

$ 0

242,683,000

638,000

242,045,000

242,683,000

$ 0

Boston Properties Limited Partnership | 180 CityPoint [Member] | Development

N/A

$ 0

214,754,000

10,908,000

108,970,000

94,876,000

214,754,000

$ 541,000

Boston Properties Limited Partnership | 300 Binney Street | Development

N/A

$ 18,080,000

51,262,000

38,454,000

18,080,000

27,805,000

61,911,000

107,796,000

$ 6,719,000

Boston Properties Limited Partnership | 103 CityPoint | Development

N/A

$ 0

88,188,000

4,670,000

3,025,000

8,672,000

71,821,000

88,188,000

$ 18,000

Boston Properties Limited Partnership | Reston Next Office Phase II | Development

N/A

$ 0

39,201,000

39,201,000

39,201,000

$ 0

Boston Properties Limited Partnership | Reston Next Retail | Development

N/A

$ 0

8,367,000

8,367,000

8,367,000

$ 0

Boston Properties Limited Partnership | 343 Madison Avenue | Land

N/A

$ 0

206,052,000

158,885,000

47,167,000

206,052,000

$ 0

Boston Properties Limited Partnership | 777 Harrison Street | Land

N/A

$ 144,647,000

28,334,000

47,000

172,934,000

172,981,000

$ 29,000

Boston Properties Limited Partnership | Back Bay Station Master Plan | Land

N/A

$ 0

78,150,000

78,150,000

78,150,000

$ 0

Boston Properties Limited Partnership | 3625 - 3635 Peterson Way | Land

N/A

$ 63,206,000

5,173,000

68,379,000

68,379,000

$ 0

Boston Properties Limited Partnership | Kendall Center Master Plan | Land

N/A

$ 0

48,857,000

48,857,000

48,857,000

$ 0

Boston Properties Limited Partnership | North First Master Plan | Land

N/A

$ 35,004,000

4,068,000

39,072,000

39,072,000

$ 0

Boston Properties Limited Partnership | Plaza at Almaden | Land

N/A

$ 0

38,163,000

38,163,000

38,163,000

$ 0

Boston Properties Limited Partnership | CityPoint South Master Plan | Land

N/A

$ 0

25,594,000

25,594,000

25,594,000

$ 0

Boston Properties Limited Partnership | Springfield Metro Center | Land

N/A

$ 0

19,896,000

19,896,000

19,896,000

$ 0

Boston Properties Limited Partnership | Reston Gateway Master Plan | Land

N/A

$ 0

13,908,000

13,908,000

13,908,000

$ 0

Boston Properties Limited Partnership | Weston Quarry | Land

N/A

$ 0

1,249,000

1,249,000

1,249,000

$ 0

Boston Properties Limited Partnership | Broad Run Business Park | Land

N/A

$ 0

1,186,000

1,186,000

1,186,000

$ 0

Boston Properties Limited Partnership | Reston Overlook Master Plan | Land

N/A

$ 0

80,000

80,000

80,000

$ 0

Stockholders' Equity / Partners' Capital

N/A

[1]	Includes unamortized deferred financing costs and fair value debt adjustment totaling approximately $(33.6) million.
[2]	Includes Right of Use Assets - Finance Leases and Right of Use Assets - Operating Leases of approximately $378,276 and $324,298, respectively.
[3]	Includes Right of Use Assets - Finance Leases of approximately $23,404.
[4]	Includes pre-development costs.
[5]	Includes pre-development costs.
[6]	See Note 4.
[7]	Depreciation of the buildings and improvements are calculated over lives ranging from the life of the lease to 40 years.
[8]	This property is encumbered with the mortgage note shown at 355 Main Street. See Note 7 to the Consolidated Financial Statements.
[9]	Includes unamortized deferred financing costs and fair value debt adjustment totaling approximately $(33.6) million.
[10]	Includes Right of Use Assets - Finance Leases and Right of Use Assets - Operating Leases of approximately $378,276 and $324,298, respectively.
[11]	Includes Right of Use Assets - Finance Leases of approximately $23,404.
[12]	Includes pre-development costs.
[13]	Depreciation of the buildings and improvements are calculated over lives ranging from the life of the lease to 40 years.
[14]	This property is encumbered with the mortgage note shown at 355 Main Street. See Note 7 to the Consolidated Financial Statements.

Segment Information (Schedule Of Reconciliation Of Net Operating Income To Net Income) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Net income attributable to the Company common shareholders / unitholders	$ 190,215	$ 848,947	$ 496,223
Preferred Stock Redemption Charge	0	0	(6,412)
Preferred dividends / distributions	0	0	(2,560)
Noncontrolling interest-common units of the Operating Partnership	(22,548)	(96,780)	(55,931)
Noncontrolling interest in property partnerships	(78,661)	(74,857)	(70,806)
Interest expense	(579,572)	(437,139)	(423,346)
Losses from early extinguishment of debt	0	0	45,182
Losses from interest rate contracts	79	0	0
Company's share of net operating income from joint ventures	(1,998,776)	(1,929,527)	(1,814,288)
Loss from unconsolidated joint ventures	239,543	59,840	2,570
Depreciation and amortization expense	(830,813)	(749,775)	(717,336)
Transaction costs	(4,313)	(2,905)	(5,036)
General and administrative expense	(170,158)	(146,378)	(151,573)
Unrealized Gain (Loss) on Investments	(239)	150	0
Gains (losses) from investments in securities	(5,556)	6,453	(5,626)
Other Income - assignment fee	0	(6,624)	0
Interest and other income (loss)	(69,964)	(11,940)	(5,704)
Gain on sales-type lease	0	(10,058)	0
Gains on sales of real estate	(517)	(437,019)	(123,660)
Segment Reconciling Items
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Net income attributable to the Company common shareholders / unitholders	190,215	848,947	496,223
Preferred Stock Redemption Charge	0	0	6,412
Preferred dividends / distributions	0	0	2,560
Noncontrolling interest-common units of the Operating Partnership	22,548	96,780	55,931
Noncontrolling interest in property partnerships	78,661	74,857	70,806
Interest expense	579,572	437,139	423,346
Losses from early extinguishment of debt	0	0	45,182
Losses from interest rate contracts	79	0	0
Loss from unconsolidated joint ventures	239,543	59,840	2,570
Depreciation and amortization expense	830,813	749,775	717,336
Transaction costs	4,313	2,905	5,036
Operating expense	17,771	15,450	12,487
General and administrative expense	170,158	146,378	151,573
Unrealized Gain (Loss) on Investments	239	(150)	0
Gains (losses) from investments in securities	5,556	(6,453)	5,626
Other Income - assignment fee	0	6,624	0
Interest and other income (loss)	69,964	11,940	5,704
Gain on sales-type lease	0	10,058	0
Gains on sales of real estate	517	437,019	123,660
Other revenue	17,771	15,450	12,487
Company's share of Net Operating Income	1,965,106	1,883,796	1,735,740
Unconsolidated Joint Ventures [Member]
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Interest expense	(227,537)	(154,065)	(108,884)
Losses from early extinguishment of debt	3	1,327	0
Company's share of net operating income from joint ventures			(107,756)
Loss from unconsolidated joint ventures	239,543	59,840	2,570
Depreciation and amortization expense	(197,228)	(181,041)	(147,121)
Transaction costs	(301)	(837)	(470)
Gain on sales-type lease	(2,737)	0	0
Unconsolidated Joint Ventures [Member] \| Segment Reconciling Items
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Company's share of net operating income from joint ventures	160,695	146,081	107,756
Boston Properties Limited Partnership
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Net income attributable to the Company common shareholders / unitholders	219,771	957,265	561,993
Preferred Stock Redemption Charge	0	0	(6,412)
Preferred dividends / distributions	0	0	(2,560)
Noncontrolling interest in property partnerships	(78,661)	(74,857)	(70,806)
Interest expense	(579,572)	(437,139)	(423,346)
Losses from early extinguishment of debt	0	0	45,182
Losses from interest rate contracts	79	0	0
Loss from unconsolidated joint ventures	239,543	59,840	2,570
Depreciation and amortization expense	(823,805)	(742,293)
Transaction costs	(4,313)	(2,905)	(5,036)
General and administrative expense	(170,158)	(146,378)	(151,573)
Unrealized Gain (Loss) on Investments	(239)	150	0
Gains (losses) from investments in securities	(5,556)	6,453	(5,626)
Other Income - assignment fee	0	(6,624)	0
Interest and other income (loss)	(69,964)	(11,940)	(5,704)
Gain on sales-type lease	0	(10,058)	0
Gains on sales of real estate	(517)	(441,075)	(125,198)
Boston Properties Limited Partnership \| Segment Reconciling Items
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Net income attributable to the Company common shareholders / unitholders	219,771	957,265	561,993
Preferred Stock Redemption Charge	0	0	6,412
Preferred dividends / distributions	0	0	2,560
Noncontrolling interest in property partnerships	78,661	74,857	70,806
Interest expense	579,572	437,139	423,346
Losses from early extinguishment of debt	0	0	45,182
Losses from interest rate contracts	79	0	0
Loss from unconsolidated joint ventures	239,543	59,840	2,570
Depreciation and amortization expense	823,805	742,293	709,035
Transaction costs	4,313	2,905	5,036
Operating expense	17,771	15,450	12,487
General and administrative expense	170,158	146,378	151,573
Unrealized Gain (Loss) on Investments	239	(150)	0
Gains (losses) from investments in securities	5,556	(6,453)	5,626
Other Income - assignment fee	0	6,624	0
Interest and other income (loss)	69,964	11,940	5,704
Gain on sales-type lease	0	10,058	0
Gains on sales of real estate	517	441,075	125,198
Other revenue	17,771	15,450	12,487
Company's share of Net Operating Income	1,965,106	1,883,796	1,735,740
Management Service [Member]
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Other revenue	(40,850)	(28,056)	(27,697)
Management Service [Member] \| Segment Reconciling Items
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Other revenue	40,850	28,056	27,697
Management Service [Member] \| Boston Properties Limited Partnership
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Other revenue	(40,850)	(28,056)	(27,697)
Management Service [Member] \| Boston Properties Limited Partnership \| Segment Reconciling Items
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Other revenue	40,850	28,056	27,697
Noncontrolling interest - property partnerships [Member]
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Company's share of net operating income from joint ventures	194,365	191,812	186,304
Noncontrolling interest - property partnerships [Member] \| Segment Reconciling Items
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Company's share of net operating income from joint ventures	194,365	191,812	186,304
Noncontrolling interest - property partnerships [Member] \| Boston Properties Limited Partnership \| Segment Reconciling Items
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Company's share of net operating income from joint ventures	$ 194,365	$ 191,812	$ 186,304

Stockholders' Equity / Partners' Capital

12 Months Ended

Dec. 31, 2023

Equity [Abstract]

11. Stockholders’ Equity / Partners’ Capital

As of December 31, 2023, BXP had 156,940,866 shares of Common Stock outstanding.

As of December 31, 2023, BXP owned 1,755,150 general partnership units and 155,185,716 limited partnership units in BPLP.

On May 17, 2023, BXP renewed its “at the market” (“ATM”) stock offering program through which it may sell from time to time up to an aggregate of $600.0 million of its Common Stock through sales agents over a three-year period. Under the ATM stock offering program, BXP may also engage in forward sale transactions with affiliates of certain sales agents for the sale of its Common Stock on a forward basis. This program replaced BXP’s prior $600.0 million ATM stock offering program that was scheduled to expire on May 22, 2023. BXP intends to use the net proceeds from any offering for general business purposes, which may include investment opportunities and debt reduction. No shares of Common Stock have been issued under this ATM stock offering program.

During the years ended December 31, 2023 and December 31, 2022, BXP did not issue any shares of Common Stock upon the exercise of options to purchase Common Stock. As a result of the applicable exercise period ending, 103,641 options were forfeited during the year ended December 31, 2023. As of December 31, 2023, BXP does not have any outstanding options.

During the years ended December 31, 2023 and December 31, 2022, BXP issued 102,699 and 182,929 shares of Common Stock, respectively, in connection with the redemption of an equal number of redeemable OP Units from limited partners.

The following table presents BXP’s dividends per share and BPLP’s distributions per OP Unit and LTIP Unit paid or declared during the years ended December 31, 2023, 2022 and 2021:


Record Date	Payment Date	Dividend (Per Share)	Distribution (Per Unit)
December 29, 2023	January 30, 2024	$0.98	$0.98
September 29, 2023	October 31, 2023	$0.98	$0.98
June 30, 2023	July 31, 2023	$0.98	$0.98
March 31, 2023	April 28, 2023	$0.98	$0.98
December 30, 2022	January 30, 2023	$0.98	$0.98
September 30, 2022	October 31, 2022	$0.98	$0.98
June 30, 2022	July 29, 2022	$0.98	$0.98
March 31, 2022	April 29, 2022	$0.98	$0.98
December 31, 2021	January 28, 2022	$0.98	$0.98
September 30, 2021	October 29, 2021	$0.98	$0.98
June 30, 2021	July 30, 2021	$0.98	$0.98
March 31, 2021	April 30, 2021	$0.98	$0.98
December 31, 2020	January 28, 2021	$0.98	$0.98

Preferred Stock

At December 31, 2020, BXP had 80,000 shares (8,000,000 depositary shares each representing 1/100th of a share) outstanding of its 5.25% Series B Cumulative Redeemable Preferred Stock (“Series B Preferred Stock”) with a liquidation preference of $2,500.00 per share ($25.00 per depositary share). BXP paid cumulative cash dividends on the Series B Preferred Stock at a rate of 5.25% per annum of the $2,500.00 liquidation preference per share.

BXP did not have the right to redeem the Series B Preferred Stock prior to March 27, 2018, except in certain circumstances relating to the preservation of BXP’s REIT status. On and after March 27, 2018, BXP, at its option, could redeem the Series B Preferred Stock for a cash redemption price of $2,500.00 per share ($25.00 per depositary share), plus all accrued and unpaid dividends. The Series B Preferred Stock was not redeemable by the holders, had no maturity date and was not convertible into any other security of BXP or its affiliates.

On March 2, 2021, BXP issued a redemption notice for 80,000 shares of its Series B Preferred Stock, which constituted all of the outstanding Series B Preferred Stock, and the corresponding depositary shares, each representing 1/100th of a share of Series B Preferred Stock. The redemption price per share of Series B Preferred Stock was $2,500, plus all accrued and unpaid dividends to, but not including, the redemption date, totaling $2,516.41 per share. On March 31, 2021, the Company transferred the full redemption price for all outstanding shares of Series B Preferred Stock of approximately $201.3 million, including approximately $1.3 million of accrued and unpaid dividends to, but not including, the redemption date, to the redemption agent. The excess of the redemption price over the carrying value of the Series B Preferred Stock and BPLP’s Series B Preferred Units of approximately $6.4 million relates to the original issuance costs and is reflected as a reduction to Net Income Attributable to Boston Properties, Inc. Common Shareholders and Net Income Attributable to Boston Properties Limited Partnership Common Unitholders on the Consolidated Statement of Operations.

On April 1, 2021, BXP redeemed all of the outstanding shares of Series B Preferred Stock and all of the outstanding depositary shares. In connection with the redemption of the Series B Preferred Stock, all of the Series B Preferred Units, which had terms and preferences generally mirroring those of the Series B Preferred Stock, were redeemed by BPLP.

The following table presents BXP’s dividend per share on its Series B Preferred Stock paid during the year ended December 31, 2021:

Record Date

Payment Date

Dividend (Per Share)

February 5, 2021

February 16, 2021

$32.8125

The entire disclosure for equity.

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Earnings Per Share / Common Unit

Earnings Per Share / Common Unit

12 Months Ended

Dec. 31, 2023

Earnings Per Share [Abstract]

13. Earnings Per Share / Common Unit

BXP

The following table provides a reconciliation of both the net income attributable to Boston Properties, Inc. common shareholders and the number of common shares used in the computation of basic earnings per share (“EPS”), which is calculated by dividing net income attributable to Boston Properties, Inc. common shareholders by the weighted-average number of common shares outstanding during the period. Unvested share-based payment awards that contain non-forfeitable rights to dividends or dividend equivalents (whether paid or unpaid) are also participating securities. As such, unvested restricted common stock of BXP and BPLP’s LTIP Units, 2012 OPP Units and MYLTIP Units are considered participating securities. Participating securities are included in the computation of basic EPS of BXP using the two-class method. Participating securities are included in the computation of diluted EPS of BXP using the if-converted method if the impact is dilutive. Because the 2012 OPP Units and 2013 - 2020 MYLTIP Units required, and the 2021 - 2023 MYLTIP Units require, BXP to outperform absolute and/or relative return thresholds, unless such thresholds have been met by the end of the applicable reporting period, BXP excludes such units from the diluted EPS calculation. Other potentially dilutive common shares, including stock options, restricted stock and other securities of BPLP that are exchangeable for BXP’s Common Stock, and the related impact on earnings, are considered when calculating diluted EPS.


	Year ended December 31, 2023
	Income (Numerator)		Shares (Denominator)	Per Share Amount
	(in thousands, except for per share amounts)
Basic Earnings:
Net income attributable to Boston Properties, Inc. common shareholders	$	190,215	156,863	$	1.21
Allocation of undistributed earnings to participating securities	—		—	—
Net income attributable to Boston Properties, Inc. common shareholders	190,215		156,863	1.21
Effect of Dilutive Securities:
Stock Based Compensation	—		338	—
Diluted Earnings:
Net income attributable to Boston Properties, Inc. common shareholders	$	190,215	157,201	$	1.21

	Year ended December 31, 2022
	Income (Numerator)		Shares (Denominator)	Per Share Amount
	(in thousands, except for per share amounts)
Basic Earnings:
Net income attributable to Boston Properties, Inc. common shareholders	$	848,947	156,726	$	5.42
Allocation of undistributed earnings to participating securities	(891)		—	(0.01)
Net income attributable to Boston Properties, Inc. common shareholders	848,056		156,726	5.41
Effect of Dilutive Securities:
Stock Based Compensation	—		411	(0.01)
Diluted Earnings:
Net income attributable to Boston Properties, Inc. common shareholders	$	848,056	157,137	$	5.40

	Year ended December 31, 2021
	Income (Numerator)		Shares (Denominator)	Per Share Amount
	(in thousands, except for per share amounts)
Basic Earnings:
Net income attributable to Boston Properties, Inc. common shareholders	$	496,223	156,116	$	3.18
Allocation of undistributed earnings to participating securities	—		—	—
Net income attributable to Boston Properties, Inc. common shareholders	496,223		156,116	3.18
Effect of Dilutive Securities:
Stock Based Compensation	—		260	(0.01)
Diluted Earnings:
Net income attributable to Boston Properties, Inc. common shareholders	$	496,223	156,376	$	3.17

BPLP

The following table provides a reconciliation of both the net income attributable to Boston Properties Limited Partnership common unitholders and the number of common units used in the computation of basic earnings per common unit, which is calculated by dividing net income attributable to Boston Properties Limited Partnership common unitholders by the weighted-average number of common units outstanding during the period. Unvested share-based payment awards that contain non-forfeitable rights to dividends or dividend equivalents (whether paid or unpaid) are also participating securities. As such, unvested restricted common stock of BXP and BPLP’s LTIP Units, 2012 OPP Units and MYLTIP Units are considered participating securities. Participating securities are included in the computation of basic earnings per common unit using the two-class method. Participating securities are included in the computation of diluted earnings per common unit using the if-converted method if the impact is dilutive. Because the 2012 OPP Units and 2013 - 2020 MYLTIP Units required, and the 2021 - 2023 MYLTIP Units require, BXP to outperform absolute and/or relative return thresholds, unless such thresholds have been met by the end of the applicable reporting period, BPLP excludes such units from the diluted earnings per common unit calculation. Other potentially dilutive common units and the related impact on earnings are considered when calculating diluted earnings per common unit. Included in the number of units (the denominator) below are approximately 17,933,000, 17,634,000 and 17,034,000 redeemable common units for the years ended December 31, 2023, 2022 and 2021, respectively.


	Year ended December 31, 2023
	Income (Numerator)		Units (Denominator)	Per Unit Amount
	(in thousands, except for per unit amounts)
Basic Earnings:
Net income attributable to Boston Properties Limited Partnership common unitholders	$	219,771	174,796	$	1.26
Allocation of undistributed earnings to participating securities	—		—	—
Net income attributable to Boston Properties Limited Partnership common unitholders	219,771		174,796	$	1.26
Effect of Dilutive Securities:
Stock Based Compensation	—		338	(0.01)
Diluted Earnings:
Net income attributable to Boston Properties Limited Partnership common unitholders	$	219,771	175,134	$	1.25

	Year ended December 31, 2022
	Income (Numerator)		Units (Denominator)	Per Unit Amount
	(in thousands, except for per unit amounts)
Basic Earnings:
Net income attributable to Boston Properties Limited Partnership common unitholders	$	957,265	174,360	$	5.49
Allocation of undistributed earnings to participating securities	(991)		—	(0.01)
Net income attributable to Boston Properties Limited Partnership common unitholders	956,274		174,360	5.48
Effect of Dilutive Securities:
Stock Based Compensation	—		411	(0.01)
Diluted Earnings:
Net income attributable to Boston Properties Limited Partnership common unitholders	$	956,274	174,771	$	5.47


	Year ended December 31, 2021
	Income (Numerator)		Units (Denominator)	Per Unit Amount
	(in thousands, except for per unit amounts)
Basic Earnings:
Net income attributable to Boston Properties Limited Partnership common unitholders	$	561,993	173,150	$	3.25
Allocation of undistributed earnings to participating securities	—		—	—
Net income attributable to Boston Properties Limited Partnership common unitholders	561,993		173,150	$	3.25
Effect of Dilutive Securities:
Stock Based Compensation	—		260	(0.01)
Diluted Earnings:
Net income attributable to Boston Properties Limited Partnership common unitholders	$	561,993	173,410	$	3.24

Employee Benefits Plan (Details) - USD ($) $ in Thousands	12 Months Ended
Employee Benefits Plan (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Defined Contribution Plan Disclosure [Line Items]
Defined Contribution Plan, Employer Matching Contribution, Percent of Match	200.00%
Defined Contribution Plan, Employer Matching Contribution, Percent of Employees' Gross Pay	3.00%
Defined Contribution Plan, Employer Matching Contribution, Eligible Earnings Limit by IRS Amount	$ 330	$ 305	$ 290
Defined Contribution Plan, Employer Discretionary Contribution Amount	5,400	4,800	$ 4,700
Separate Unrestricted Cash For Deferred Compensation Plan.	36,100	32,300
Deferred Compensation Liability, Current and Noncurrent	35,300	31,700
Officer [Member]
Defined Contribution Plan Disclosure [Line Items]
Separate Unrestricted Cash For Deferred Compensation Plan.	$ 35,300	$ 31,700

Mortgage Notes Payable, Net (Details)
$ in Thousands

12 Months Ended

Dec. 14, 2023

USD ($)

ft²

buildings

Oct. 26, 2023

USD ($)

ft²

buildings

Dec. 31, 2023

USD ($)

Rate

Dec. 31, 2022

USD ($)

Rate

Debt Instrument, Collateral

each collateralized by one or more buildings and related land included in real estate assets

Number Of Variable Mortgage Loans

$ 4,166,379

$ 3,272,368

Joint Venture Partner [Member] | Santa Monica Business Park [Member]

^[1]

55.00%

45.00%

Number of real estate properties | buildings

1,200,000

Mortgages [Member]

$ 4,166,379

$ 3,300,000

Mortgages [Member] | 325 Main Street, 355 Main Street, 90 Broadway and Kendall Center Green Garage Properties [Member]

4,200,000

$ 600,000

Mortgages [Member] | 325 Main Street, 355 Main Street, 90 Broadway and Kendall Center Green Garage Properties [Member] | Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate

$ 600,000

Debt Instrument, Description of Variable Rate Basis

2.25%

SOFR

Number of real estate properties | buildings

898,000

Debt - Total loan amount

$ 600,000

Mortgages [Member] | Santa Monica Business Park [Member]

$ 300,000

Mortgages [Member] | Santa Monica Business Park [Member] | Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate

$ 300,000

1.38%

Debt Instrument, Description of Variable Rate Basis

$ 300,000

SOFR

$ 295,500

Debt - Total loan amount

300,000

Fixed Rate Mortgage [Member]

$ 300,000

Debt, Weighted Average Interest Rate | Rate

$ 4,200,000

$ 3,300,000

3.70%

3.24%

Fixed Rate Mortgage [Member] | Minimum [Member]

Debt Instrument, Interest Rate, Stated Percentage | Rate

2.79%

Fixed Rate Mortgage [Member] | Maximum [Member]

Debt Instrument, Interest Rate, Stated Percentage | Rate

6.04%

3.43%

[1]	During the year ended December 31, 2023, the Company completed the acquisition of its joint venture partner’s 45% ownership interest in Santa Monica Business Park, as described below in this Note 6 and Note 3.

2021 Credit Facility and 2023 Unsecured Term Loan Compliance (Details) - 2021 Credit Facility and 2023 Unsecured Term Loan [Member]	12 Months Ended
	Dec. 31, 2023
Debt Instrument [Line Items]
Debt Instrument, Covenant Description	Among other covenants, the 2021 Credit Facility and the 2023 Unsecured Term Loan require that BPLP maintain on an ongoing basis: (1) a leverage ratio not to exceed 60%, however, the leverage ratio may increase to no greater than 65% provided that it is reduced back to 60% within one year, (2) a secured debt leverage ratio not to exceed 55%, (3) a fixed charge coverage ratio of at least 1.40, (4) an unsecured debt leverage ratio not to exceed 60%, however, the unsecured debt leverage ratio may increase to no greater than 65% provided that it is reduced to 60% within one year, (5) an unsecured debt interest coverage ratio of at least 1.75 and (6) limitations on permitted investments.
Leverage ratio	60.00%
Leverage ratio - maximum	65.00%
Secured debt leverage ratio - maximum	55.00%
Fixed charge coverage - minimum	1.40
Unsecured debt leverage ratio	60.00%
Unsecured debt leverage ratio - maximum	65.00%
Unsecured debt interest coverage ratio	1.75
Debt Instrument, Covenant Compliance	At December 31, 2023, BPLP was in compliance with each of these financial and other covenant requirements.

Stock Option and Incentive Plan (Tables)

12 Months Ended

Dec. 31, 2023

Text Block [Abstract]

Share-based Payment Arrangement, Option, Activity

A summary of the status of BXP’s stock options as of December 31, 2023, 2022 and 2021 and changes during the years then ended are presented below:


	Shares	Weighted-Average Exercise Price
Outstanding at December 31, 2020	351,561	$	96.97
Exercised	(247,920)	$	96.95
Outstanding at December 31, 2021	103,641	$	97.01
Exercised	—	$	—
Outstanding at December 31, 2022	103,641	$	97.01
Forfeited	(103,641)	$	—
Outstanding at December 31, 2023	—	$	—

Organization	12 Months Ended
Organization	Dec. 31, 2023
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization	1. Organization BXP is a fully integrated, self-administered and self-managed REIT. BXP is the sole general partner of BPLP, its operating partnership, and at December 31, 2023 owned an approximate 89.4% (89.6% at December 31, 2022) general and limited partnership interest in BPLP. Unless stated otherwise or the context requires, the “Company” refers to BXP and its subsidiaries, including BPLP and its consolidated subsidiaries. Partnership interests in BPLP include: •common units of partnership interest (also referred to as “OP Units”) and •long term incentive units of partnership interest (also referred to as “LTIP Units”) Unless specifically noted otherwise, all references to OP Units exclude units held by BXP. A holder of an OP Unit may present the OP Unit to BPLP for redemption at any time (subject to restrictions agreed upon at the time of issuance of OP Units to particular holders that may restrict such redemption right for a period of time, generally one year from issuance). Upon presentation of an OP Unit for redemption, BPLP is obligated to redeem the OP Unit for cash equal to the value of a share of common stock of BXP (“Common Stock”). In lieu of such cash redemption, BXP may elect to acquire the OP Unit for one share of Common Stock. Because the number of shares of Common Stock outstanding at all times equals the number of OP Units that BXP owns, one share of Common Stock is generally the economic equivalent of one OP Unit, and the quarterly distribution that may be paid to the holder of an OP Unit equals the quarterly dividend that may be paid to the holder of a share of Common Stock. The Company uses LTIP Units as a form of time-based, restricted equity compensation and as a form of performance-based equity compensation for employees, and has previously granted LTIP Units in the form of (1) 2012 outperformance plan awards (“2012 OPP Units”) and (2) 2013 - 2023 multi-year, long-term incentive program awards (also referred to as “MYLTIP Units”), each of which, upon the satisfaction of certain performance-based and time-based vesting conditions, is convertible into one OP Unit. The three-year measurement periods for the 2012 OPP Units and the 2013 - 2020 MYLTIP Units have ended and BXP’s total stockholder return (“TSR”) was sufficient for employees to earn and therefore become eligible to vest in a portion of the awards. Unless and until they are earned, the rights, preferences and privileges of the 2021 - 2023 MYLTIP Units differ from other LTIP Units granted to employees (including the 2012 OPP Units and the 2013 - 2020 MYLTIP Units, which have been earned). Therefore, unless specifically noted otherwise, all references to LTIP Units exclude the 2021 - 2023 MYLTIP Units. LTIP Units (including the earned 2012 OPP Units and the earned 2013 - 2020 MYLTIP Units), whether vested or not, will receive the same quarterly per unit distributions as OP Units, which equal per share dividends on Common Stock (See Notes 10, 15 and 17). Properties At December 31, 2023, the Company owned or had joint venture interests in a portfolio of 188 commercial real estate properties (the “Properties”) aggregating approximately 53.3 million net rentable square feet of primarily premier workplaces, including 10 properties under construction/redevelopment totaling approximately 2.7 million net rentable square feet. At December 31, 2023, the Properties consisted of: •167 office and life sciences properties (including seven properties under construction/redevelopment); •14 retail properties (including two properties under construction/redevelopment); •six residential properties (including one property under construction); and •one hotel. The Company considers premier workplaces to be well-located buildings that are modern structures or have been modernized to compete with newer buildings and professionally managed and maintained. As such, these properties attract high-quality tenants and command upper-tier rental rates. All references to acres and square footage in the Notes are unaudited. Basis of Presentation The accompanying consolidated financial statements are presented using the accrual basis of accounting in conformity with accounting principles generally accepted in the United States of America. BXP does not have any other significant assets, liabilities or operations, other than its investment in BPLP, nor does it have employees of its own. BPLP, not BXP, generally executes all significant business relationships other than transactions involving securities of BXP. All majority-owned subsidiaries and joint ventures over which the Company has financial and operating control and variable interest entities (“VIEs”) in which the Company has determined it is the primary beneficiary are included in the consolidated financial statements. All significant intercompany balances and transactions have been eliminated in consolidation. The Company accounts for all other unconsolidated joint ventures using the equity method of accounting. Accordingly, the Company’s share of the earnings of these joint ventures and companies is included in consolidated net income. Variable Interest Entities (VIEs) Consolidated VIEs are those for which the Company is considered to be the primary beneficiary of a VIE. The primary beneficiary is the entity that has a controlling financial interest in the VIE, which is defined by the entity having both of the following characteristics: (1) the power to direct the activities that, when taken together, most significantly impact the VIE’s performance and (2) the obligation to absorb losses or the right to receive the returns from the VIE that could potentially be significant to the VIE. The assets of each VIE are only available to satisfy such VIE's respective liabilities. The Company has identified eight entities that are VIEs as of December 31, 2023 and has determined that it is the primary beneficiary for all of these entities as of December 31, 2023. Consolidated Variable Interest Entities As of December 31, 2023, BXP has identified eight consolidated VIEs, including BPLP. Excluding BPLP, the consolidated VIEs consisted of (i) the following five in-service properties: 767 Fifth Avenue (the General Motors Building), Times Square Tower, 601 Lexington Avenue, Atlantic Wharf Office Building and 100 Federal Street, (ii) 343 Madison Avenue, which is categorized as land held for future development, and (iii) 300 Binney Street which is currently under redevelopment. The Company consolidates these VIEs because it is the primary beneficiary. The third parties’ interests in these consolidated entities (excluding BPLP’s interest) are reflected as noncontrolling interests in property partnerships in the accompanying consolidated financial statements (See Note 10). In addition, BXP’s only significant asset is its investment in BPLP and, consequently, substantially all of BXP’s assets and liabilities are the assets and liabilities of BPLP. Variable Interest Entities Not Consolidated As of December 31, 2023, the Company does not have any unconsolidated joint ventures that are classified as VIEs.

Real Estate Asset Acquisition (Details) - Santa Monica Business Park [Member] $ in Thousands	Dec. 14, 2023 USD ($)
Asset Acquisition [Line Items]
Land	$ 46,360
Building and improvements	390,305
Tenant Improvements	20,116
Net Assets Acquired	490,720
Mortgages [Member]
Asset Acquisition [Line Items]
Liabilities, Fair Value Adjustment	4,491
In-Place Lease Intangibles
Asset Acquisition [Line Items]
Lease Intangibles	74,022
Above Market Lease Intangibles [Member]
Asset Acquisition [Line Items]
Lease Intangibles	6,715
Below Market Lease [Member]
Asset Acquisition [Line Items]
Lease Intangibles	(4,630)
Ground Lease
Asset Acquisition [Line Items]
Lease Intangibles	$ (46,659)

Leases (Tables)

12 Months Ended

Dec. 31, 2023

Lessee, Operating Lease, Liability, Maturity

Lease, Cost

The following table provides lease cost information for the Company’s operating and finance leases for the years ended December 31, 2023, 2022 and 2021 (in thousands):


	Year ended December 31,
Lease costs	2023		2022		2021
Operating lease costs (1)	$	14,451	$	12,700	$	13,151
Finance lease costs
Amortization of right of use asset (2)	$	2,821	$	697	$	547
Interest on lease liabilities (3)	$	13,747	$	3,236	$	2,471

_______________

The following table provides other quantitative information for the Company’s operating and finance leases as of December 31, 2023 and December 31, 2022:


	December 31, 2023		December 31, 2022
Other information
Weighted-average remaining lease term (in years)
Operating leases	70		49
Finance leases	60		68
Weighted-average discount rate
Operating leases	6.6	%	5.7	%
Finance leases	6.1	%	6.2	%

The following table provides a maturity analysis for the Company’s lease liabilities related to its operating and finance leases as of December 31, 2023 (in thousands):


	Operating		Finance
2024 (1)	$	29,989	$	70,370
2025	35,733		32,232
2026	10,100		31,972
2027	9,885		32,170
2028 (1)	14,637		118,232
Thereafter	3,546,537		1,342,174
Total lease payments	3,646,881		1,627,150
Less:
Interest portion	3,296,490		1,209,189
Present value of lease payments	$	350,391	$	417,961

_______________

The following table provides a maturity analysis for the Company’s lease liabilities related to its operating and finance leases as of December 31, 2022 (in thousands):


	Operating		Finance
2023	$	22,415	$	9,306
2024 (1)	22,274		49,343
2025	10,308		9,971
2026	10,100		10,166
2027	9,885		10,364
Thereafter	528,915		1,352,647
Total lease payments	603,897		1,441,797
Less:
Interest portion	399,211		1,192,462
Present value of lease payments	$	204,686	$	249,335

_______________

Finance Lease, Liability, Maturity

The following table provides a maturity analysis for the Company’s lease liabilities related to its operating and finance leases as of December 31, 2023 (in thousands):


	Operating		Finance
2024 (1)	$	29,989	$	70,370
2025	35,733		32,232
2026	10,100		31,972
2027	9,885		32,170
2028 (1)	14,637		118,232
Thereafter	3,546,537		1,342,174
Total lease payments	3,646,881		1,627,150
Less:
Interest portion	3,296,490		1,209,189
Present value of lease payments	$	350,391	$	417,961

_______________

The following table provides a maturity analysis for the Company’s lease liabilities related to its operating and finance leases as of December 31, 2022 (in thousands):


	Operating		Finance
2023	$	22,415	$	9,306
2024 (1)	22,274		49,343
2025	10,308		9,971
2026	10,100		10,166
2027	9,885		10,364
Thereafter	528,915		1,352,647
Total lease payments	603,897		1,441,797
Less:
Interest portion	399,211		1,192,462
Present value of lease payments	$	204,686	$	249,335

_______________

Lessor, Lease, Description [Line Items]

Operating Lease, Lease Income [Table Text Block]

Lessor

Operating Leases


	Year ended December 31,
Lease Revenue	2023		2022		2021
Fixed contractual payments	$	2,503,106	$	2,426,007	$	2,319,362
Variable lease payments	550,641		492,361		433,652
Sales-type lease	926		—		—
	$	3,054,673	$	2,918,368	$	2,753,014

Lessor, Operating Lease, Payments to be Received, Maturity


Years Ending December 31,
2024	$	2,420,047
2025	2,444,826
2026	2,379,371
2027	2,281,437
2028	2,140,919
Thereafter	15,592,965

Sales-type and Direct Financing Leases, Lease Receivable, Maturity

The following table provides the future contractual payments to be received as of December 31, 2023 (in thousands):


	December 31, 2023
2024	$	31
2025	124
2026	372
2027	756
2028	775
Thereafter	267,474
Total lease payments to be received	269,532
Less:
Interest portion	255,579
Sales-type lease receivable	13,953
Unguaranteed residual asset	18
Current expected credit loss adjustment	(267)
Sales-type lease receivable, net	$	13,704

The following table provides the future contractual payments to be received as of December 31, 2022 (in thousands):


	December 31, 2022
2023	$	—
2024	31
2025	124
2026	372
2027	756
Thereafter	268,249
Total lease payments to be received	269,532
Less:
Interest portion	256,504
Sales-type lease receivable	13,028
Unguaranteed residual asset	17
Current expected credit loss adjustment	(234)
Sales-type lease receivable, net	$	12,811

Leases (Details) - USD ($) $ in Thousands	12 Months Ended
Leases (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Leases [Abstract]
Fixed contractual payments	$ 2,503,106	$ 2,426,007	$ 2,319,362
Variable lease payments	550,641	492,361	433,652
Sales-type lease revenue	926	0	0
Lease	$ 3,054,673	$ 2,918,368	$ 2,753,014

Stockholders' Equity / Partners' Capital Narrative (Details) $ / shares in Units, $ in Thousands					12 Months Ended
	May 17, 2023 USD ($) yr	Apr. 01, 2021	Mar. 31, 2021 USD ($)	Mar. 02, 2021 USD ($) $ / shares shares	Dec. 31, 2023 USD ($) shares	Dec. 31, 2022 USD ($) shares	Dec. 31, 2021 USD ($) shares	Dec. 31, 2020 $ / shares shares	May 22, 2020 USD ($)	Mar. 27, 2018 $ / shares
Class of Stock [Line Items]
Common Stock, Shares, Outstanding					156,940,866	156,757,867
General Partners' Capital Account, Units Outstanding (in units)					1,755,150
Limited Partners' Capital Account, Units Outstanding (in units)					155,185,716
Options exercised					0	0	(247,920)
Shares of Common Stock issued in connection with redemption of an equal number of OP Units (in shares)					102,699	182,929
Preferred Stock Redemption Premium \| $					$ 0	$ 0	$ 6,412
Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Forfeitures in Period					103,641
Preferred stock / units, shares / units outstanding (in shares / units)					0	0
ATM Program [Member]
Class of Stock [Line Items]
At The Market Stock Offering Program Aggregate Value Of Common Stock \| $	$ 600,000								$ 600,000
At Market Stock Offering Program Maximum Length Of Sale (in years) \| yr	3
Series B Cumulative Redeemable Preferred Stock / Unit [Member]
Class of Stock [Line Items]
Series B Liquidation Preference Per Share/ Unit \| $ / shares								$ 2,500		$ 2,500
Series B, Dividend Rate, Percentage								5.25%
Preferred Stock, Redemption Price Per Share \| $ / shares				$ 2,500
Preferred Stock Redemption Price Per Share, plus accrued and unpaid dividends \| $ / shares				$ 2,516.41
Preferred Stock, Redemption Amount \| $				$ 201,300
Redeemable Preferred Stock Dividends \| $				$ 1,300
Preferred Stock Redemption Premium \| $			$ 6,400
Preferred Stock, Redemption Date		Apr. 01, 2021
Preferred stock / units, shares / units outstanding (in shares / units)				80,000				80,000
Depository shares of Series B Cumulative Redeemable Preferred
Class of Stock [Line Items]
Series B Liquidation Preference Per Share/ Unit \| $ / shares								$ 25.00		$ 25.00
Preferred stock / units, shares / units outstanding (in shares / units)								8,000,000

Noncontrolling Interests

12 Months Ended

Dec. 31, 2023

Noncontrolling Interest [Abstract]

Noncontrolling Interest Disclosure [Text Block]

10. Noncontrolling Interests

Noncontrolling interests relate to the interests in BPLP not owned by BXP and interests in consolidated property partnerships not wholly-owned by the Company. As of December 31, 2023, the noncontrolling interests in BPLP consisted of 16,508,277 OP Units, 2,065,861 LTIP Units (including 480,511 LTIP Units earned by employees under the Company’s multi-year long-term incentive awards granted between 2012 and 2020 (i.e., 2012 OPP and 2013 - 2020 MYLTIP awards)), 349,267 2021 MYLTIP Units, 252,151 2022 MYLTIP Units and 322,053 2023 MYLTIP Units held by parties other than BXP.

Noncontrolling Interest—Common Units

During the years ended December 31, 2023 and 2022, 102,699 and 182,929 OP Units, respectively, were presented by the holders for redemption (including an aggregate of 94,863 and 78,249 OP Units, respectively, issued upon conversion of LTIP Units, 2012 OPP Units and MYLTIP Units) and were redeemed by BXP in exchange for an equal number of shares of Common Stock.

At December 31, 2023, BPLP had outstanding 349,267 2021 MYLTIP Units, 252,151 2022 MYLTIP Units and 322,053 2023 MYLTIP Units. Prior to the end of the respective three-year performance period for each plan, holders of MYLTIP Units are entitled to receive per unit distributions equal to one-tenth (10%) of the regular quarterly distributions payable on an OP Unit, but will not be entitled to receive any special distributions. After the three-year performance period for each plan has ended, (1) the number of MYLTIP Units, both vested and unvested, that MYLTIP award recipients have earned, if any, based on the establishment of a performance pool, will be entitled to receive distributions in an amount per unit equal to distributions, both regular and special, payable on an OP Unit and (2) with respect to the 2021 - 2023 MYLTIP Units, the Company will make a “catch-up” cash payment on the MYLTIP Units that are ultimately earned in an amount equal to the regular and special dividends, if any, declared during the performance period on a number of shares of Common Stock agreed to the number of 2021 - 2023 MYLTIP Units that are earned, less the distributions actually paid during the performance period on all of the awarded 2021 - 2023 MYLTIP Units.

On December 14, 2021, BPLP issued approximately 866,503 OP Units as partial consideration for the acquisition of 360 Park Avenue South in New York, New York. The OP Units issued totaled approximately $99.7 million based on the average closing price per share of BXP’s common stock for the five trading days immediately preceding the closing date.


Record Date	Payment Date	Distributions per OP Unit and LTIP Unit	Distributions per MYLTIP Unit
December 29, 2023	January 30, 2024	$0.98	$0.098
September 29, 2023	October 31, 2023	$0.98	$0.098
June 30, 2023	July 31, 2023	$0.98	$0.098
March 31, 2023	April 28, 2023	$0.98	$0.098




December 30, 2022	January 30, 2023	$0.98	$0.098


Record Date	Payment Date	Distributions per OP Unit and LTIP Unit	Distributions per MYLTIP Unit
December 30, 2022	January 30, 2023	$0.98	$0.098
September 30, 2022	October 31, 2022	$0.98	$0.098
June 30, 2022	July 29, 2022	$0.98	$0.098
March 31, 2022	April 29, 2022	$0.98	$0.098
December 31, 2021	January 28, 2022	$0.98	$0.098


Record Date	Payment Date	Distributions per OP Unit and LTIP Unit	Distributions per MYLTIP Unit
December 31, 2021	January 28, 2022	$0.98	$0.098
September 30, 2021	October 29, 2021	$0.98	$0.098
June 30, 2021	July 30, 2021	$0.98	$0.098
March 31, 2021	April 30, 2021	$0.98	$0.098
December 31, 2020	January 28, 2021	$0.98	$0.098

A holder of an OP Unit may present the OP Unit to BPLP for redemption at any time (subject to restrictions agreed upon at the time of issuance of OP Units to particular holders that may restrict such redemption right for a period of time, generally one year from issuance). Upon presentation of an OP Unit for redemption, BPLP must redeem the OP Unit for cash equal to the then value of a share of Common Stock of BXP. BXP may, in its sole discretion, elect to assume and satisfy the redemption obligation by paying either cash or issuing one share of Common Stock. The value of the OP Units (other than OP Units owned by BXP), and LTIP Units (including the 2012 OPP Units and 2013 - 2020 MYLTIP Units), assuming in each case that all conditions had been met for the conversion thereof, had all of such units been redeemed at December 31, 2023 was approximately $1.3 billion based on the last reported price of a share of Common Stock on the New York Stock Exchange of $70.17 per share on December 29, 2023.

Noncontrolling Interests—Property Partnerships

The noncontrolling interests in property partnerships consist of the outside equity interests in ventures that are consolidated with the financial results of the Company because the Company exercises control over the entities that own the properties. The equity interests in these ventures that are not owned by the Company, totaling approximately $1.6 billion and $1.5 billion at December 31, 2023 and December 31, 2022, respectively, are included in Noncontrolling Interests—Property Partnerships on the accompanying Consolidated Balance Sheets.

On July 28, 2023, the Company entered into a joint venture agreement with an institutional investor for the future development of 343 Madison Avenue located on Madison Avenue between 44th and 45th Streets in New York City, New York adjacent to Grand Central Station. Prior to the formation of the joint venture, the Company and the institutional investor were engaged in a collaborative arrangement. The Company owns a 55% interest in the joint venture and its partner owns a 45% interest, and the Company will provide customary development, property management, and leasing services. The joint venture partner contributed approximately $4.8 million in cash and $17.5 million in improvements and prepaid ground rent for their 45% ownership interest in the joint venture. The Company contributed approximately $5.9 million in cash and $21.4 million in improvements and prepaid ground rent for its 55% ownership interest in the joint venture. The transaction did not qualify as a sale of real estate for financial reporting purposes as the Company continues to effectively control this property and will continue to account for the property on a consolidated basis in its financial statements, see Note 4.

On November 13, 2023, the Company entered into agreements to sell a 45% interest in 290 Binney Street and 300 Binney Street, two life sciences development projects located in Kendall Square in Cambridge, Massachusetts, to an institutional investor (See Note 3). Upon entry into the agreement, the Company completed the sale of a 45% interest in 300 Binney Street. The institutional investor funded approximately $212.9 million in cash at closing for its investment in 300 Binney Street, including future costs to fund completion of the development project. The Company will retain a 55% ownership interest in the joint venture and fund all remaining costs of the development. The Company has accounted for the transaction as an equity transaction and has recognized noncontrolling interest in its Consolidated Balance Sheets totaling approximately $35.5 million, which is equal to 45% of the aggregate carrying value of the total equity of the property immediately prior to the transaction. The difference between the cash proceeds received and the noncontrolling interest recognized, which was approximately $177.4 million, has been reflected as an increase in additional paid-in capital in the Company’s Consolidated Balance Sheets. The transaction did not qualify as a sale of real estate for financial reporting purposes as the Company continues to effectively control the property and thus will continue to account for the property on a consolidated basis in its

financial statements and no gain was recognized in the Consolidated Statements of Operations. As the institutional investor pre-funded their contributions, it resulted in the partners’ equity balances not being proportionate to each partners’ ownership percentage. As a result, at the end of each reporting period, there will be a reallocation of the partners’ equity balances such that the ending balance in each partners’ capital account reflects each partners’ claim on net assets. These adjustments will impact additional paid-in capital and noncontrolling interest in property partnerships in the Company’s Consolidated Balance Sheets. For the period ended December 31, 2023, the adjustment was approximately $17.0 million. The Company will provide customary development, property management and leasing services to the joint venture.

Real Estate (Tables)

12 Months Ended

Dec. 31, 2023

Schedule of Real Estate Properties

BXP

Real estate consisted of the following at December 31, 2023 and December 31, 2022 (in thousands):


	December 31, 2023		December 31, 2022
Land	$	5,251,224	$	5,189,811
Right of use assets - finance leases (1)	401,680		237,510
Right of use assets - operating leases (1)	324,298		167,351
Land held for future development (2)	697,061		721,501
Buildings and improvements	16,607,756		15,820,724
Tenant improvements	3,592,172		3,200,743
Furniture, fixtures and equipment	53,716		50,310
Construction in progress	547,280		406,574
Total	27,475,187		25,794,524
Less: Accumulated depreciation	(6,881,728)		(6,298,082)
	$	20,593,459	$	19,496,442

_______________

(1)See Note 4.

(2)Includes pre-development costs.

Schedule of Finite-Lived Intangible Assets, Future Amortization Expense

The following table summarizes the scheduled amortization of the Company’s acquired “above-” and “below-market” lease intangibles for each of the five succeeding years (in thousands).


	Acquired Above-Market Lease Intangibles		Acquired Below-Market Lease Intangibles
2024	$	3,985	$	9,961
2025	1,880		9,756
2026	982		8,602
2027	743		5,432
2028	605		2,125

Schedule of Finite-Lived Intangible Assets, Future Amortization Expense

Asset Acquisition

The following table summarizes the allocation of the relative fair value of the net assets the Company received at the date of acquisition for Santa Monica Business Park (in thousands):


Land and site improvements	$	46,360
Building and improvements	390,305
Tenant improvements	20,116
In-place lease intangibles	74,022
Above-market lease intangibles	6,715
Below-market lease intangibles	(4,630)
Ground lease intangible	(46,659)
Mortgage note payable adjustment	4,491
Net assets acquired	$	490,720


	Acquired In-Place Lease Intangibles		Acquired Ground Lease Intangible		Acquired Above-Market Lease Intangibles		Acquired Below-Market Lease Intangible
2024	$	32,362	$	10,979	$	3,584	$	1,109
2025	20,782		10,979		1,491		944
2026	7,986		10,979		593		910
2027	4,078		10,979		354		910
2028	2,726		2,193		216		553

Schedule of Acquired Finite-Lived Intangible Assets by Major Class


	Acquired In-Place Lease Intangibles	Acquired Ground Lease Intangible	Acquired Above-Market Lease Intangibles	Acquired Below-Market Lease Intangible
Weighted-average useful life	2.9	4.2	2.3	5.1