Fluor completed the sale of its headquarters.

Escrow on the $340-million deal closed following eight hours of document signing. Trammell Crow Co., in partnership with Winthrop Financial Associates of Boston, acquired the property. Fluor, an Irvine engineering and construction company, is selling its assets in response to a prolonged slump in the worldwide engineering market. Trammell Crow said it plans to build hotels, office buildings and retail space on the 122 acres surrounding Fluor’s headquarters, which the company is leasing back.