EXHIBIT 32.1

CERTIFICATION OF CHIEF EXECUTIVE OFFICER

PURSUANT TO SECTION 906 OF THE SARBANES-OXLEY ACT OF 2002

The undersigned, being the Chief Executive Officer of Archstone-Smith Operating Trust, a Maryland real estate investment trust (the ”Issuer”), hereby certifies that the Quarterly Report on Form 10-Q (the “Periodic Report”) of the Issuer for the quarter ended September 30, 2007 which accompanies this certification, fully complies with the requirements of Section 13(a) of the Securities Exchange Act of 1934 (15 U.S.C. §78m(a)) and that the information contained in the Periodic Report fairly presents, in all material respects, the financial condition and results of operations of the Issuer.

Date: November 9, 2007

/s/ R. SCOT SELLERS

R. Scot Sellers, Chief Executive Officer