The U.S. Department of State, Bureau of Overseas Buildings Operations manages 3,500 properties at 289 diplomatic missions located around the world. More than 230 are recognized as heritage properties by U.S. and host governments for their historical, cultural, or architectural merit. Twenty-five are within UNESCO World Heritage Sites. Property types include office buildings, educational centers, official residences, guest houses and staff apartments, a museum, and a cemetery, among others. Building materials and systems range from adobe, timber frame, and load-bearing stone to glass-curtain walls and reinforced concrete.
To fulfill its stewardship mandate under U.S. preservation law and to comply with regulations in the host nations, the Department of State inaugurated two programs: an inventory of significant properties and an honorary registration of select properties of exceptional importance within U.S. diplomatic history.