EXHIBIT 10.7

COMPLETION GUARANTY

THIS COMPLETION GUARANTY (" Guaranty "), dated as of March 18, 2008 is made by PRIME GROUP REALTY, L.P. , a Delaware limited partnership (the " Guarantor "), in favor of GENERAL ELECTRIC CAPITAL CORPORATION , a Delaware corporation (" GECC "), as Collateral Agent for the Note B Lenders that are or become a party to the Loan Agreement described below (in such capacity, " Collateral Agent "), and is executed pursuant to (i) that certain Loan Agreement (Loan B) dated as of the date of this Guaranty between 330 N. WABASH AVENUE, L.L.C. , a Delaware limited liability company (the " Borrower "), the lenders from time to time a party thereto (the " Note B Lenders "), and Collateral Agent (such Loan Agreement, as it may from time to time be supplemented, modified and amended, being referred to in this Guaranty as the " Agreement "), and (ii) that certain Promissory Note B dated as of the date of this Guaranty executed by Borrower in favor GECC as a lender (such Promissory Note B, together with all promissory notes delivered in substitution or exchange thereof, in each case as the same may be from time to time consolidated, split, amended, modified, extended, renewed, substituted and/or supplemented, shall be collectively referred to in this Guaranty as " Note   B "), the provisions of which are incorporated in this Guaranty by reference. Capitalized terms used in this Guaranty and not otherwise defined are used with the meanings set forth in the Agreement or in Note B.

Subject to the terms and conditions set forth in the Agreement, Note B and the Mortgages (as hereinafter defined), the Note B Lenders have agreed to make a loans to the Borrower in the aggregate amount of up to $100,000,000.00 (collectively, " Loan   B ") to provide a portion of the financing for the Project (as defined in the Agreement). Loan B will be secured by (i) that certain Mortgage, Assignment of Leases, Security Agreement and Fixture Filing and (ii) that certain Leasehold Mortgage, Assignment of Leases, Security Agreement and Fixture Filing (collectively, the " Mortgages "), each executed by the Borrower in favor of the Collateral Agent (on behalf of the Note B Lenders and "Lender A" described therein) and encumbering a portion of the Project. As a condition of the obligation of the Note B Lenders to make Loan B, the Guarantor is required to execute and deliver to Collateral Agent this Guaranty.

To induce the Note B Lenders to make Loan B and for other valuable consideration, the Guarantor agrees as follows:

1.          Guaranteed Obligations . The Guarantor absolutely and unconditionally guarantees the punctual and complete payment and performance when due of all of the following obligations of the Borrower (collectively, the " Guaranteed Obligations "):

(a)       the Borrower's obligation to deposit or cause to be deposited into the TI/LC/CapEx/DS Reserve described in Section 34 of Note B an amount equal to the "Reserve Deficiency" described therein, as and when required by Section 34 of Note B;

(b)       the Borrower's obligation to complete, in accordance with Section 5.5 of the Agreement, each Stage of Capex Work commenced by Borrower, which obligation includes, as to each such Stage, the obligation to complete all Capex Work for such Stage within the Stage Construction Schedule for such Stage, Lien-free and in accordance with the construction contracts and plans and specifications therefor approved by the Collateral Agent.

The Guarantor agrees that Collateral Agent's damages for any breach of the guaranty set forth in clause (b) above, with respect to any Stage, shall be the positive difference, if any, between,(i) the full cost of completing (in accordance with Section 5.5 of the Agreement) all of the remaining Capex Work for such Stage (as of the date Borrower is in breach of its completion obligation), and (ii) the amount of an then-remaining undisbursed funds in the Stage Budget for such Stage. Guarantor waives any right it may have to assert that any other measure of damages is an applicable or adequate remedy for any breach of the guaranty set forth in clause (b), above.

Upon the occurrence of any Event of Default, all Guaranteed Obligations shall, at the option of Collateral Agent, immediately become due and payable by the Guarantor without protest, presentment, notice of dishonor, demand or further notice of any kind, all of which are expressly waived by the Guarantor, and irrespective of whether any Guaranteed Obligations have then become due and payable by the Borrower or any other Person (each of the Borrower and any such other Person other than Guarantor being referred to in this Guaranty as an " other Borrower Party ").

2.          Nature of Guaranty . This Guaranty is a guaranty of payment and performance and not of collection, is continuing in nature and applies to all Guaranteed Obligations, whether existing now or in the future, including (a) interest and other Guaranteed Obligations arising or accruing after bankruptcy of any other Borrower Party or any sale or other disposition of any security for this Guaranty or for the obligations of any other Borrower Party (any such security being referred to in this Guaranty as the " Security "), and (b) any Guaranteed Obligations that survive repayment of Loan B. This Guaranty and any Security for this Guaranty shall continue to be effective or be reinstated, as the case may be, if at any time any payment or performance of any Guaranteed Obligations is rescinded or must otherwise be returned by Collateral Agent, the Note B Lenders or any other Person upon the bankruptcy, insolvency or reorganization of any other Borrower Party or otherwise, all as though such payment or performance had not occurred. The Guarantor shall have no authority to revoke this Guaranty, but if any such revocation shall be deemed to have occurred by operation of law or otherwise, the provisions of this Guaranty shall continue to apply notwithstanding such revocation.

3.          Obligations Independent . The obligations of the Guarantor under this Guaranty are independent of the obligations of any other Borrower Party under the Loan Documents (such obligations of any other Borrower Party, including the Borrower's obligations in respect of the Guaranteed Obligations, being referred to in this Guaranty as the " Other Obligations ") and any Security, and the enforceability of any Security for this Guaranty is

likewise independent of any such Other Obligations and any other Security. Collateral Agent may bring action against the Guarantor and otherwise enforce this Guaranty or any Security for this Guaranty without bringing action against any other Borrower Party or joining any other Borrower Party in any action against the Guarantor, and otherwise independently of any other right, power or remedy (each, a " Remedy ") that may be available to Lender at any time with respect to any Other Obligations or Security. The Guarantor waives any right to require Collateral Agent or Lenders at any time to proceed against any other Borrower Party, apply any Security or otherwise enforce, proceed against or exhaust any Other Obligations or Security or pursue any other Remedy in Collateral Agent's or Note B Lenders' power.

4.          Action with Respect to Other Obligations or Security . The Guarantor authorizes Collateral Agent and each Note B Lender, without notice or demand and without affecting its liability under or the enforceability of this Guaranty or any Security for this Guaranty, from time to time to:

(a)       supplement, modify, amend, renew, extend, accept partial payments or performance on or otherwise change the time, manner or place of payment or performance or the interest rate or other terms or the amount of, or release, reconvey, terminate, waive, abandon, subordinate, exchange, substitute, transfer or consent to the transfer of or enter into or give any other agreement, approval, waiver or consent with respect to or in exchange for any Other Obligations or Security or any of the Loan Documents (including release the Fourteenth Floor (as defined in Note B) pursuant to Section 29 of Note B);

(c)       release any other B