CONTRIBUTION AGREEMENT

EXHIBIT 10.3

CONTRIBUTION AGREEMENT

By and Between

FIFTH AVENUE 58/59 ACQUISITION CO. L.P.

(“ Fifth Avenue ”)

and

BOSTON PROPERTIES LIMITED PARTNERSHIP

(“BPLP”)

Dated as of May 23, 2008

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CONTRIBUTION AGREEMENT

THIS AGREEMENT (“ Agreement ”), is made as of the 23 ^rd day of May, 2008, by and between FIFTH AVENUE 58/59 ACQUISITION CO. L.P., a Delaware limited partnership (“Fifth Avenue”), with an address at c/o Macklowe Properties, 767 Fifth Avenue, New York, NY 10153-0023, and BOSTON PROPERTIES LIMITED PARTNERSHIP, a Delaware limited partnership, having an address c/o Boston Properties, Inc., Prudential Center, 800 Boylston Street, Suite 1900, Boston, Massachusetts 02199 (“ BPLP ”).

W I T N E S S E T H :

NOW, THEREFORE , in consideration of the mutual covenants and agreements herein contained and other good and valuable consideration, the receipt and sufficiency of which are hereby acknowledged, BPLP and Fifth Avenue hereby agree as follows:

ARTICLE 1 — DEFINITIONS

1.1 Defined Terms . The following terms as used in this Agreement will have the meanings attributed to them as set forth below unless the context clearly requires another meaning. The terms set forth do not constitute all of the defined terms set forth in this Agreement.

(a) “ Agreement ” means this Contribution Agreement, as the same may be amended, restated, supplemented or otherwise modified from time to time in accordance with the terms hereof.

(b) “ Assignment Agreement ” means the Assignment and Assumption Agreement in the form attached hereto as Exhibit A .

(c) “ BPLP ” shall have the meaning specified in the preamble to this Agreement.

(d) “ BPLP’s Knowledge ” means the actual, and not constructive, knowledge of any of Mortimer B. Zuckerman, Robert Selsam and Matthew Mayer (but none of such individuals shall have any personal liability hereunder for any representations or warranties made by BPLP to BPLP’s Knowledge).

(e) “ Business Day ” means any day except Saturday, Sunday and any day which shall be a legal holiday or a day on which banking institutions in the State of New York generally are authorized or required by law or other government actions to close.

(f) “ Boston Properties ” means Boston Properties, Inc., a Delaware corporation and the general partner of BPLP, or any successor to Boston Properties, Inc. pursuant to a merger, consolidation, business combination, reclassification or reorganization.

(g) “ Closing ” shall mean the closing of the transactions contemplated by Article 2 hereof.

(h) “ Closing Date ” shall mean the date of the Closing, which shall be immediately after Fifth Avenue acquires the Equity Interest pursuant to the JV Contribution Agreement.

(i) “ Code ” means the Internal Revenue Code of 1986, as amended, and rules and regulations thereunder.

(j) “ Common Stock ” means shares of Boston Properties common stock, par value $0.01 per share, or the common stock of any successor to Boston Properties pursuant to a merger, consolidation, business combination, reclassification or reorganization.

(k) “ Company ” shall have the meaning specified in the recitals to this Agreement.

(l) “ Credit Line Loan ” shall have the meaning assigned to such term in the Tax Protection Agreement.

(m) “ Debt Financed Distribution ” shall have the meaning set forth in Section 2.1 of this Agreement.

(n) “ Equity Interest ” shall have the meaning set forth in the recitals to this Agreement.

(o) “ Fifth Avenue ” shall have the meaning set forth in the preamble to this Agreement.

(p) “ Fifth Avenue’s Knowledge ” means the actual, and not constructive, knowledge of any of Harry Macklowe and William Macklowe (but none of such individuals shall have any personal liability hereunder for any representations or warranties made by Fifth Avenue to Fifth Avenue’s Knowledge).

(q) “ Governmental Entity ” means any agency, bureau, commission, court, department, official, political subdivision, tribunal, or other instrumentality of any government, whether federal, state or local, domestic or foreign.

(r) “ Individual Legal Costs ” means the legal fees and expenses incurred, respectively, by BPLP and Fifth Avenue and their respective affiliates in connection with the transactions contemplated herein. Individual Legal Costs include, without limitation, all legal fees and expenses associated the Transaction Documents.

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(s) “ Investor Questionnaire ” means the Investor Questionnaire in substantially the form attached hereto as Exhibit B .

(t) “ Law ” means any constitutional provision, federal, state or local law, statute, ordinance, rule or regulation or any Order of any Governmental Entity (including, without limitation, environmental and tax laws).

(u) “ Lien ” means, with respect to any property or asset, any mortgage, pledge, encumbrance, charge or security interest of any kind in or on such property or asset or the revenue or income therefrom and “Liens” means each and every Lien, collectively.

(v) “ Limited Partner Signature Page ” means the Limited Partner Signature Page in substantially the form attached hereto as Exhibit F .

(w) “ Lock-Up Period ” shall have the meaning set forth is Section 5.2 of this Agreement.

(x) “ OPUs ” means the common units of limited partnership interests of BPLP to be issued by BPLP to Fifth Avenue pursuant to Section 2.1 hereof.

(y) “ Order ” means any decree, injunction, judgment, order, ruling, assessment or writ, including, without limitation, any executive mandate of any Governmental Entity.

(z) “ Partnership Agreement ” means the Second Amended and Restated Agreement of Limited Partnership of BPLP dated as of June 29, 1998, as amended.

(aa) “ Partnership Amendment ” means the next sequentially numbered amendment to the Partnership Agreement as of the Closing Date in substantially the form attached hereto as Exhibit D , pursuant to which the OPUs are issued to Fifth Avenue in accordance with this Agreement and Fifth Avenue is admitted as a limited partner of BPLP.

(bb) “ Person ” means an individual, partnership, corporation, limited liability company, trust or unincorporated organization, or a governmental agency or political subdivision thereof.

(cc) “ Qualified Credit Line Guaranty ” means the guaranty of the Credit Line Loan provided for in the Tax Protection Agreement.

(dd) “ Registration Rights and Lock-Up Agreement ” means the Registration Rights and Lock-up Agreement in substantially the form attached hereto as Exhibit C .

(ee) “ Related Party ” means, with respect to any person or entity, any other person or entity whose ownership of Common Stock would be attributed to the first such person or entity under either Code Section 544 (as modified by Code Section 856(h)(1)(B)) or Code Section 318 (as modified by Code 856(d)(5)).

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(ff) “ Securities Act ” means the Securities Act of 1933, as amended, and the rules and regulations of the Securities and Exchange Commission promulgated thereunder.

(gg) “ Tax Protection Agreement ” means the Tax Protection Agreement of even date herewith between the Company, Fifth Avenue and BPLP in substantially the form attached hereto as Exhibit E .

(hh) “ Transaction Documents ” shall mean collectively, this Agreement, the Tax Protection Agreement, the Partnership Amendment, the Investor Questionnaire and the Registration Rights and Lock-Up Agreement.

(ii) “ Transfer Taxes ” shall have the meaning set forth in Section 5.7 hereof.

(jj) “ Treasury Regulation ” means a regulation promulgated by the United States Treasury Department pursuant to the Code.

1.2 Interpretation . When the context in which words are used in this Agreement indicates that such is the intent, singular words shall include the plural and vice versa and masculine words shall include the feminine and the neuter genders and vice versa. References to Articles, Sections, Exhibits, Schedules or other subdivisions are to the appropriate subdivisions of this Agreement unless the context otherwise requires. The words “herein”, “hereof”, and “hereunder” and other words of similar import refer to this Agreement as a whole and not to any particular Article, Section, Exhibit, Schedule or other subdivision.

ARTICLE 2 — CONTRIBUTION AND RELATED TRANSACTIONS

2.1 Transactions and Deliveries at the Closing . On the Closing Date, the parties shall cause the following transactions to occur, and related documents to be fully executed and delivered, in the following order:

(a) BPLP shall close on the Credit Line Loan and obtain aggregate loan proceeds equal to the amount of the Debt Financed Distribution and Fifth Avenue and Harry Macklowe will enter into a Qualified Credit Line Guaranty.

(b) Fifth Avenue shall contribute, transfer and assign to BPLP, and BPLP shall accept, by execution and delivery of the Assignment Agreement, subject to the terms and conditions stated herein, the Equity Interest.

(c) In consideration of and immediately upon the contribution of the Equity Interest to BPLP, BPLP shall:

(i) transfer TWO HUNDRED MILLION DOLLARS ($200,000,000) to Fifth Avenue by wire transfer of immediately available funds to one or more accounts to be designated by Fifth Avenue (the “ Debt Financed Distribution”) , it being agreed by the parties that the Debt Financed Distribution shall be funded solely with proceeds from the Credit Line Loan and is intended by the parties to qualify as a “debt-financed transfer” under Treasury Regulations Section 1.707-5(b); and

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(ii) issue to Fifth Avenue a number of OPUs calculated by dividing TEN MILLION AND 00/100 DOLLARS ($10,000,000) by the average closing price of a share of Common Stock on the New York Stock Exchange for the five (5) trading days immediately preceding the Closing Date (the “ Closing Day Value ”).

2.2 Closing Date . The Closing shall occur on the Closing Date at the same location as the closing of the transactions contemplated by the JV Contribution Agreement or at such other place in the Borough of Manhattan, City, County and State of New York, as the parties may designate. Time shall be of the essence to the Closing Date under this Agreement.

2.3 Issuance of OPUs .

(a) Fifth Avenue shall execute and deliver a Limited Partner Signature Page, BPLP shall execute and deliver the Partnership Amendment evidencing issuance to Fifth Avenue of the number of OPUs required to be issued pursuant to Section 2.1 hereof, and Fifth Avenue shall thereupon be admitted as a limited partner of BPLP with an initial capital account equal to TEN MILLION AND 00/100 DOLLARS ($10,000,000).

(b) Delivery of OPUs to Fifth Avenue is expressly conditioned upon Fifth Avenue delivering to BPLP an Investor Questionnaire properly completed and executed.

(c) Fifth Avenue agrees to indemnify, save and hold harmless BPLP and its partners, officers, employees, agents, attorneys, representatives and their respective affiliates from and against from and against any and all costs, losses, taxes, liabilities, obligations, damages, lawsuits, deficiencies, claims, demands, and expenses (whether or not arising out of third-party claims), including, without limitation, interest, penalties, and attorneys’ fees and all amounts paid in investigation, defense or settlement of any of the foregoing, incurred in connection with, arising out of, resulting from or incident to (1) any document prepared or distributed by Fifth Avenue to, or other communications with, any of its partners in connection with the transactions contemplated by this Agreement, including documents, if any, distributed in connection with the consent or election of any of its partners, provided, however, that the foregoing shall not apply to information supplied by BPLP in writing to Fifth Avenue as specified in the Investor Questionnaire and (2) obligations or liabilities of Fifth Avenue to any current or former partner, employee, consultant or agent on account of such person’s present or former interest in or right to participate in the revenues or profits of Fifth Avenue. This indemnification shall be unlimited as to amount and shall survive for a period of five (5) years after the date hereof.

ARTICLE 3 — REPRESENTATIONS AND WARRANTIES OF FIFTH AVENUE

Assuming the consummation of the transactions contemplated by this Agreement, Fifth Avenue represents and warrants to BPLP as of the date hereof as follows:

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3.1 Organization, Good Standing and Authority . Fifth Avenue is a limited partnership duly organized, validly existing and in good standing under the laws of the State of Delaware, and it is authorized to consummate the transactions contemplated hereby and by the other Transaction Documents to which it is a party and fulfill all of its obligations hereunder, under the Transaction Documents and under all documents contemplated hereunder or thereunder to be executed by it, and has all necessary power to execute and deliver this Agreement, the other Transaction Documents to which it is a party and all documents contemplated hereunder or thereunder to be executed by it, and to perform all of its obligations hereunder or thereunder.

3.2 Authorization and Binding Effect . This Agreement and all documents contemplated hereunder (including all of the other Transaction Documents) to be executed by Fifth Avenue when executed and delivered will have been duly authorized by all requisite action on the part of Fifth Avenue and its partners and are, or will be upon execution and delivery, as applicable, the valid and legally binding obligations of Fifth Avenue enforceable in accordance with their respective terms, subject to bankruptcy, insolvency, fraudulent transfer, reorganization, moratorium and similar laws of general applicability relating to or affecting creditors’ rights generally and to general principles of equity.

3.3 Contributed Equity Interest . As of the Closing Date and immediately prior to the contribution of the Equity Interest to BPLP as contemplated hereby, Fifth Avenue will be the sole owner of the Equity Interest. Prior to the consummation of the transactions contemplated hereby, Fifth Avenue will not encumber the Equity Interest or transfer the Equity Interest to any person other than BPLP. As of the Closing Date (but prior to the consummation of the transactions contemplated hereby), Fifth Avenue will own the Equity Interest beneficially and of record free and clear of any Liens, and will have full power and authority to transfer the Equity Interest free and clear of any Liens.

3.4 Conflicting Agreements and Other Matters . Neither the execution and delivery of this Agreement, the other Transaction Documents or any other instrument or agreement contemplated hereunder or thereunder by Fifth Avenue nor fulfillment and compliance with the terms and provisions hereof and thereof, nor the assignment of the Equity Interests to BPLP, nor the acquisition of the OPUs as contemplated by this Agreement will:

(a) violate any provisions of Law having applicability to Fifth Avenue or any of its properties or assets;

(b) conflict with or result in a violation of any provisions of the partnership agreement of Fifth Avenue;

(c) require any consent, approval, filing or notice under, or conflict with or result in a breach of or constitute a default under or accelerate any right under any note, bond, mortgage, license, indenture or loan or credit agreement, or any other agreement or instrument to which Fifth Avenue is a party or by which any of its properties or assets