GUARANTY AGREEMENT

Exhibit 99.4

GUARANTY AGREEMENT

THIS GUARANTY AGREEMENT (this “Guaranty”) is executed as of August 7, 2006, by XXXXXXX PROPERTIES, L.P. a Maryland limited partnership, having an address at 0000 Xxxxx Xxxxxx, 0xx Xxxxx, Xxxxx Xxxxxx, Xxxxxxxxxx 00000 (“Guarantor”), for the benefit of NOMURA CREDIT & CAPITAL, INC., a Delaware corporation, having an address at Two World Financial Center, New York, New York 10281(together with its successors and assigns, “Lender”).

RECITALS:

A. Pursuant to that certain Promissory Note A-1 (“Note A-1”) and Promissory Note A-2 (“Note A-2”), each dated of even date herewith, executed by XXXXXXX PROPERTIES - 555 W. FIFTH, LLC, a Delaware limited liability company (“Tower Borrower”), having its principal place of business at 0000 Xxxxx Xxxxxx, 0xx Xxxxx, Xxxxx Xxxxxx, Xxxxxxxxxx 00000 and XXXXXXX PROPERTIES - 350 X. XXXXXXXX, LLC, a Delaware limited liability company (“Garage Borrower”), having its principal place of business at 0000 Xxxxx Xxxxxx, 0xx Xxxxx, Xxxxx Xxxxxx, Xxxxxxxxxx 00000 (each of Tower Borrower and Garage Borrower, individually, a “Borrower”, and collectively, “Borrowers”), and each payable to the order of Lender in the original principal amount of Two Hundred Twenty Nine Million Dollars and 00/100 Dollars ($229,000,000.00) (as the same may be amended, restated, replaced, supplemented, or otherwise modified from time to time, collectively, the “Note”), Borrowers have become indebted, and may from time to time be further indebted, to Lender with respect to a loan (“Loan”) in the aggregate amount of Four Hundred Fifty Eight Million and 00/100 Dollars ($458,000,000.00) made pursuant to that certain Loan Agreement, dated as of even date herewith by and among Borrowers and Lender (as the same may be amended, restated, replaced, supplemented, or otherwise modified from time to time, the “Loan Agreement”).

B. The Loan is secured by that certain Deed of Trust, Assignment of Leases and Rents, Security Agreement and Fixture Filing dated as of even date herewith (as the same may be amended, restated, replaced, supplemented, or otherwise modified from time to time, the “Security Instrument”), given by Borrowers, collectively as grantor, to First American Title Insurance Company, as trustee, for the benefit of Lender, as beneficiary, encumbering the parcels of real property known as the Gas Company Tower, 000 Xxxx Xxxxx Xxxxxx, Xxx Xxxxxxx, Xxxxxxxxxx and the World Trade Center Parking Garage, 000 Xxxxx Xxxxxxxx Xxxxxx, Xxx Xxxxxxx, Xxxxxxxxxx (each, individually, a “Property” and collectively, “Properties”) as more particularly described in the Security Instrument.

C. The Loan is evidenced, secured or governed by other instruments and documents executed in connection with the Loan (together with the Note, the Loan Agreement and the Security Instrument, collectively, the “Loan Documents”).

D. Lender is not willing to make the Loan, or otherwise extend credit, to Borrowers unless Guarantor unconditionally guarantees payment and performance to Lender of the Guaranteed Obligations (as herein defined).

E. Guarantor is the owner of a direct or indirect interest in each Borrower and as a result of such interest, Guarantor will derive substantial economic and other benefits from the making of the Loan to Borrowers.

F. All capitalized terms used but not otherwise defined herein shall have the meanings ascribed to such term in the Loan Agreement.

NOW, THEREFORE, as an inducement to Lender to make the Loan to Borrowers, and to extend such additional credit as Lender may from time to time extend under the Loan Documents, and for other good and valuable consideration, the receipt and legal sufficiency of which are hereby acknowledged, the parties do hereby agree as follows:

ARTICLE 1

NATURE AND SCOPE OF GUARANTY

1.1 Guaranty of Obligation. Guarantor hereby irrevocably and unconditionally guarantees to Lender and its successors and assigns the payment and performance of the Guaranteed Obligations as and when the same shall be due and payable, whether by lapse of time, by acceleration of maturity or otherwise. Guarantor hereby irrevocably and unconditionally covenants and agrees that it is liable for the Guaranteed Obligations as a primary obligor.

1.2 Definition of Guaranteed Obligations. As used herein, the term “Guaranteed Obligations” means:

(a) the obligations and liabilities of Borrowers to Lender for any actual loss, damage, cost, expense, liability, claim and any other obligation incurred by Lender (including attorneys’ fees and costs reasonably incurred) resulting from the following (collectively, “Losses”):

(i) fraud or intentional misrepresentation by either Borrower or Guarantor in connection with the Loan, including by reason of any claim under the Racketeer Influenced and Corrupt Organizations Act (“RICO”);

(ii) the gross negligence or willful misconduct of either Borrower, any Guarantor, either of the Principals or any other Restricted Party with respect to the Loan or the Properties;

(iii) the breach of any representation, warranty, covenant or indemnification provision in the Environmental Indemnity, the Parking Easement or the Security Instrument concerning environmental laws, hazardous substances or asbestos and any indemnification of Lender with respect thereto in any Loan Document;

(iv) the wrongful removal or destruction of any portion of the Properties by either Borrower or any Affiliate of either Borrower after the occurrence of an Event of Default, or any intentional physical waste of the Properties or any portion thereof by either Borrower or any Affiliate thereof, provided, however, such physical waste shall exclude wear and tear to the Properties or any portion thereof that occurs in the ordinary course of business of the Properties;

(v) any Legal Requirement (including RICO) mandating the forfeiture by either Borrower of either Property, or any portion thereof, because of the conduct or purported conduct of criminal activity by either Borrower or any Restricted Party in connection therewith;

(vi) any material misrepresentation, miscertification or breach of warranty by either Borrower or any Guarantor with respect to any representation, warranty or certification contained in the Loan Agreement or any other Loan Document or in any document executed in connection therewith, pursuant to any of the Loan Documents or otherwise to induce Lender to make the Loan, or any advance thereof, or to release monies from any account held by Lender (including any reserve or escrow) or to take other action with respect to the Collateral (as defined in the Security Instrument);

(vii) the misappropriation or conversion by either Borrower or any Affiliate of either Borrower thereof of:

(A) any Insurance Proceeds paid by reason of any Casualty;

(B) any Condemnation Proceeds received in connection with a Condemnation;

(D) any Rents and/or Vacant Space Rent paid more than one (1) month in advance;

provided such amounts are not applied to the payment of the Loan or the Operating Expenses of either Property;

(viii) failure to pay charges for labor or materials or other charges that can create Liens on any portion of the Properties that are superior to the Lien of the Security Instrument unless such charges are being contested in accordance with the provisions of the Loan Documents;

(ix) any security deposits, advance deposits or any other deposits collected by either Borrower or any Affiliate of either Borrower thereof with respect to either Property or any part thereof which are not delivered to Lender upon a foreclosure of either Property or action in lieu thereof, except to the extent any such security deposits were applied in accordance with the terms and conditions of any of the Leases prior to the occurrence of the Event of Default that gave rise to such foreclosure or action in lieu thereof;

(x) if either Borrower fails to permit on-site inspections of either Property, fails to provide financial information specifically required by the Loan Agreement or fails to appoint a new Manager upon the request of Lender, each as required by, and in accordance with, the terms and provisions of the Loan Agreement or the Security Instrument;

(xi) (A) if there shall be a default under either of the Master Leases beyond any applicable notice and/or cure period contained therein, or (B) if either Master Lease shall have