GUARANTY AGREEMENT

Execution Version

GUARANTY AGREEMENT

      THIS GUARANTY AGREEMENT (this “ Guaranty Agreement ”), dated as of March 10, 2008, among EACH OF THE UNDERSIGNED AND EACH OTHER PERSON WHO SHALL BECOME A PARTY HERETO BY EXECUTION OF A GUARANTY JOINDER AGREEMENT (each a “ Guarantor ” and collectively the “ Guarantors ”) and BANK OF AMERICA, N.A ., a national banking association organized and existing under the laws of the United States, as administrative agent (in such capacity, the “ Administrative Agent ”) for each of the Benefited Parties. All capitalized terms used but not otherwise defined herein shall have the meanings ascribed to such terms in the Credit Agreement.

W I T N E S S E T H :

      WHEREAS , the Benefited Parties have agreed to provide to Cogdell Spencer LP, a Delaware limited partnership (the “ Borrower ”), certain credit facilities, including a secured revolving credit facility with a letter of credit and swing line sublimit pursuant to the terms of that certain Credit Agreement dated as of March 10, 2008, among the Borrower, Cogdell Spencer Inc., a Maryland corporation (“ CSI ”), as a guarantor, the Administrative Agent and the Lenders (as from time to time amended, revised, modified, supplemented or amended and restated, the “ Credit Agreement ”); and

      WHEREAS , each Guarantor is, directly or indirectly, a Material Subsidiary, a general partner or a limited partner of the Borrower and will materially benefit from the Loans made and to be made, and the Letters of Credit issued and to be issued, under the Credit Agreement; and

      WHEREAS , each Guarantor is required to enter into this Guaranty Agreement pursuant to the terms of the Credit Agreement; and

      WHEREAS , a material part of the consideration given in connection with and as an inducement to the execution and delivery of the Credit Agreement by the Benefited Parties party thereto was the obligation of CSI to cause each Guarantor to enter into this Guaranty Agreement, and the Benefited Parties are unwilling to extend and maintain the credit facilities provided under the Loan Documents unless the Guarantors enter into this Guaranty Agreement;

      NOW, THEREFORE , in consideration of the premises and mutual covenants contained herein, the parties hereto agree as follows:

      1.  Guaranty . Each Guarantor hereby jointly and severally, unconditionally, absolutely, continually and irrevocably guarantees to the Administrative Agent for the benefit of the Benefited Parties the payment and performance in full of the Guaranteed Liabilities (as defined below). For all purposes of this Guaranty Agreement, “ Guaranteed Liabilities ” means: (a) the Borrower’s prompt payment in full, when due or declared due and at all such times, of all Obligations and all other amounts pursuant to the terms of the Credit Agreement, the Notes, and all other Loan Documents heretofore, now or at any time or times hereafter owing, arising, due

or payable from the Borrower to any one or more of the Benefited Parties, including principal, interest, premiums and fees (including, but not limited to, loan fees and reasonable fees, charges and disbursements of counsel (“ Attorney Costs ”); (b) the Borrower’s prompt, full and faithful performance, observance and discharge of each and every agreement, undertaking, covenant and provision to be performed, observed or discharged by the Borrower under the Credit Agreement, the Notes and all other Loan Documents; and (c) the prompt payment in full by each Loan Party, when due or declared due and at all such times, of obligations and liabilities now or hereafter arising under Related Swap Contracts (as defined below). The Guarantors’ obligations to the Benefited Parties under this Guaranty Agreement are hereinafter collectively referred to as the “ Guarantors’ Obligations ” and, with respect to each Guarantor individually, the “ Guarantor’s Obligations ”. Notwithstanding the foregoing, the liability of each Material Subsidiary of the Borrower individually with respect to its Guarantor’s Obligations shall be limited to an aggregate amount equal to the largest amount that would not render its obligations hereunder subject to avoidance under Section 548 of the United States Bankruptcy Code or any comparable provisions of any applicable state law.

     Each Guarantor agrees that it is jointly and severally, directly and primarily liable (subject to the limitation in the immediately preceding sentence) for the Guaranteed Liabilities.

      2.  Payment . If the Borrower shall default in payment or performance of any of the Guaranteed Liabilities, whether principal, interest, premium, fee (including, but not limited to, loan fees and Attorney Costs), or otherwise, when and as the same shall become due, and after expiration of any applicable notice, grace and cure periods, whether according to the terms of the Credit Agreement, by acceleration, or otherwise, or upon the occurrence and during the continuance of any Event of Default under the Credit Agreement, then any or all of the Guarantors will, upon demand thereof by the Administrative Agent, fully pay to the Administrative Agent, for the benefit of the Benefited Parties, subject to any restriction on each Guarantor’s Obligations set forth in Section 1 hereof, an amount equal to all the Guaranteed Liabilities then due and owing.

      3.  Absolute Rights and Obligations . This is a guaranty of payment and not of collection. The Guarantors’ Obligations under this Guaranty Agreement shall be joint and several, absolute and unconditional irrespective of, and each Guarantor hereby expressly waives, to the extent permitted by law, any defense to its obligations under this Guaranty Agreement by reason of:

     (a) any lack of legality, validity or enforceability of the Credit Agreement, of any of the Notes, of any other Loan Document, or of any other agreement or instrument creating, providing security for, or otherwise relating to any of the Guarantors’ Obligations, any of the Guaranteed Liabilities, or any other guaranty of any of the Guaranteed Liabilities (the Loan Documents and all such other agreements and instruments being collectively referred to as the “ ARelated Agreements ”);

     (b) any action taken under any of the Related Agreements, any exercise of any right or power therein conferred, any failure or omission to enforce any right conferred thereby, or any waiver of any covenant or condition therein provided;

     (c) any acceleration of the maturity of any of the Guaranteed Liabilities, of the Guarantor’s Obligations of any other Guarantor, or of any other obligations or liabilities of any Person under any of the Related Agreements;

     (d) any release, exchange, non-perfection, lapse in perfection, disposal, deterioration in value, or impairment of any security for any of the Guaranteed Liabilities, for any of the Guarantor’s Obligations of any Guarantor, or for any other obligations or liabilities of any Person under any of the Related Agreements;

     (e) any dissolution of the Borrower or any Guarantor or any other party to a Related Agreement, or the combination or consolidation of the Borrower or any Guarantor or any other party to a Related Agreement into or with another entity or any transfer or disposition of any assets of the Borrower or any Guarantor or any other party to a Related Agreement;

     (f) any extension (including, without limitation, extensions of time for payment), renewal, amendment, restructuring or restatement of, any acceptance of late or partial payments under, or any change in the amount of any borrowings or any credit facilities available under, the Credit Agreement, any of the Notes or any other Loan Document or any other Related Agreement, in whole or in part;

     (g) the existence, addition, modification, termination, reduction or impairment of value, or release of any other guaranty (or security therefor) of the Guaranteed Liabilities (including, without limitation, the Guarantor’s Obligations of any other Guarantor and obligations arising under any other Guaranty now or hereafter in effect);

     (h) any waiver of, forbearance or indulgence under, or other consent to any change in or departure from any term or provision contained in the Credit Agreement, any other Loan Document or any other Related Agreement, including, without limitation, any term pertaining to the payment or performance of any of the Guaranteed Liabilities, any of the Guarantor’s Obligations of any other Guarantor, or any of the obligations or liabilities of any party to any other Related Agreement;

     (i) any other circumstance whatsoever (with or without notice to or knowledge of any Guarantor) which may or might in any manner or to any extent vary the risks of such Guarantor, or might otherwise constitute a legal or equitable defense available to, or discharge of, a surety or a guarantor, including, without limitation, any right to require or claim that resort be had to the Borrower or any other Loan Party or to any collateral in respect of the Guaranteed Liabilities or Guarantors’ Obligations, other than repayment in full of the Guaranteed Liabilities or Guarantors’ Obligations.

It is the express purpose and intent of the parties hereto that this Guaranty Agreement and the Guarantors’ Obligations hereunder, and, as to additional Guarantors acceding to this Guaranty Agreement after the date hereof, under the applicable Guaranty Joinder Agreement, shall be

absolute and unconditional under any and all circumstances and shall not be discharged except by payment as herein provided.

      4.  Currency and Funds of Payment . All Guarantors’ Obligations will be paid in lawful currency of the United States of America and in immediately available funds, subject to any law, regulation or decree now or hereafter in effect that might in any manner affect the Guaranteed Liabilities, or the rights of any Benefited Party with respect thereto as against the Borrower, or cause or permit to be invoked any alteration in the time, amount or manner of payment by the Borrower of any or all of the Guaranteed Liabilities.

      5.  Events of Default . Without limiting the provisions of Section 2 hereof, in the event that there shall occur and be continuing an Event of Default, then notwithstanding any collateral or other security or credit support for the Guaranteed Liabilities, at the Administrative Agent’s election and without notice thereof or demand therefor, the Guarantors’ Obligations shall immediately be and become due and payable.

      6.  Subordination . Until this Guaranty Agreement is terminated in accordance with Section 22 hereof, each Guarantor hereby unconditionally subordinates all present and future debts, liabilities or obligations now or hereafter owing to such Guarantor (i) of the Borrower, to the payment in full of the Guaranteed Liabilities, (ii) of every other Guarantor (an “obligated guarantor”), to the payment in full of the Guarantor’s Obligations of such obligated guarantor, and (iii) of each other Person now or hereafter constituting a Loan Party, to the payment in full of the obligations of such Loan Party owing to any Benefited Party and arising under the Loan Documents or the Related Swap Contracts. All amounts then due under such subordinated debts, liabilities, or obligations shall, upon the occurrence and during the continuance of an Event of Default, be collected and, upon request by the Administrative Agent, paid over forthwith to the Administrative Agent for the benefit of the Benefited Parties on account of the Guaranteed Liabilities, the Guarantors’ Obligations, or such other obligations, as applicable, and, after such request and pending such payment, shall be held by such Guarantor as agent and bailee of the Benefited Parties separate and apart from all other funds, property and accounts of such Guarantor.

      7.  Suits . Each Guarantor from time to time shall pay to the Administrative Agent for the benefit of the Benefited Parties, on demand, at the Administrative Agent’s Office or such other address as the Administrative Agent shall give notice of to such Guarantor, the Guarantors’ Obligations as they become or are declared due, and in the event such payment is not made forthwith, the Administrative Agent may proceed to suit against any one or more or all of the Guarantors. At the Administrative Agent’s election, one or more and successive or concurrent suits may be brought hereon by the Administrative Agent against any one or more or all of the Guarantors, whether or not suit has been commenced against the Borrower, any other Guarantor, or any other Person and whether or not the Benefited Parties have taken or failed to take any other action to collect all or any portion of the Guaranteed Liabilities or have taken or failed to take any actions against any collateral securing payment or performance of all or any portion of the Guaranteed Liabilities, and irrespective of any event, occurrence, or condition described in Section 3 hereof.

      8.  Set-Off and Waiver . Each Guarantor waives any right to assert against any Benefited Party as a defense, counterclaim, set-off, recoupment or cross claim in respect of its Guarantor’s Obligations, any defense (legal or equitable) or other claim which such Guarantor may now or at any time hereafter have against the Borrower or any or all of the Benefited Parties without waiving any additional defenses, set-offs, counterclaims or other claims otherwise available to such Guarantor. Each Guarantor agrees that each Benefited Party and each of its Affiliates shall have a lien for all the Guarantor’s Obligations upon all deposits or deposit accounts, of any kind, or any interest in any deposits or deposit accounts, now or hereafter pledged, mortgaged, transferred or assigned to such Benefited Party or such Affiliate or otherwise in the possession or control of such Benefited Party or such Affiliate for any purpose (other than solely for safekeeping) for the account or benefit of such Guarantor, including any balance of any deposit account or of any credit of such Guarantor with such Benefited Party or such Affiliate, whether now existing or hereafter established, and hereby authorizes each Benefited Party and each of its Affiliates from and after the occurrence of an Event of Default at any time or times with or without prior notice to apply such balances or any part thereof to such of the Guarantor’s Obligations to the Benefited Parties then due and in such amounts as provided for in the Credit Agreement or otherwise as they may elect. For the purposes of this Section 8 , all remittances and property shall be deemed to be in the possession of a Benefited Party or its Affiliate as soon as the same may be put in transit to it by mail or carrier or by other bailee.

      9.  Waiver of Notice; Subrogation .

     (a) Each Guarantor hereby waives to the extent permitted by law notice of the following events or occurrences: (i) acceptance of this Guaranty Agreement; (ii) the Lenders’ heretofore, now or from time to time hereafter making Loans and issuing Letters of Credit and otherwise loaning monies or giving or extending credit to or for the benefit of the Borrower or any other Loan Party, or otherwise entering into arrangements with any Loan Party giving rise to Guaranteed Liabilities, whether pursuant to the Credit Agreement or the Notes or any other Loan Document or Related Agreement or any amendments, modifications, or supplements thereto, or replacements or extensions thereof; (iii) presentment, demand, default, non-payment, partial payment and protest; and (iv) any other event, condition, or occurrence described in Section 3 hereof. Each Guarantor agrees that each Benefited Party may heretofore, now or at any time hereafter do any or all of the foregoing in such manner, upon such terms and at such times as each Benefited Party, in its sole and absolute discretion, deems advisable, without in any way or respect impairing, affecting, reducing or releasing such Guarantor from its Guarantor’s Obligations, and each Guarantor hereby consents to each and all of the foregoing events or occurrences.

     (b) Each Guarantor hereby agrees that payment or performance by such Guarantor of its Guarantor’s Obligations under this Guaranty Agreement may be enforced by the Administrative Agent on behalf of the Benefited Parties upon demand by the Administrative Agent to such Guarantor without the Administrative Agent being required, such Guarantor expressly waiving to the extent permitted by law any right it may have to require the Administrative Agent, to (i) prosecute collection or seek to enforce or resort to any remedies against the Borrower or any other Guarantor or any

other guarantor of the Guaranteed Liabilities, or (ii) seek to enforce or resort to any remedies with respect to any security interests, Liens or encumbrances granted to the Administrative Agent or any Lender or other party to a Related Agreement by the Borrower, any other Guarantor or any other Person on account of the Guaranteed Liabilities or any guaranty thereof, IT BEING EXPRESSLY UNDERSTOOD, ACKNOWLEDGED AND AGREED TO BY SUCH GUARANTOR THAT DEMAND UNDER THIS GUARANTY AGREEMENT MAY BE MADE BY THE ADMINISTRATIVE AGENT, AND THE PROVISIONS HEREOF ENFORCED BY THE ADMINISTRATIVE AGENT, EFFECTIVE AS OF THE FIRST DATE ANY EVENT OF DEFAULT OCCURS AND IS CONTINUING UNDER THE CREDIT AGREEMENT.

     (c) Each Guarantor further agrees with respect to this Guaranty Agreement that it shall have no right of subrogation, reimbursement, contribution or indemnity, nor any right of recourse to security for the Guaranteed Liabilities unless and until 93 days immediately following the Facility Termination Date shall have elapsed without the filing or commencement, by or against any Loan Party, of any state or federal action, suit, petition or proceeding seeking any reorganization, liquidation or other relief or arrangement in respect of