The Office of the Supervising Architect was an agency of the United States Treasury Department that designed federal government buildings from 1852 to 1939. The office handled some of the most important architectural commissions of the nineteenth and twentieth centuries. Among its creations are the well-known State, War, and Navy building (now the Eisenhower Executive Office Building) in Washington, DC, the San Francisco Mint Building, and smaller post offices that have served communities for decades, many recognized as National Historic Landmarks, listed in the National Register of Historic Places, or designated as local landmarks.