The Architect of the Capitol is responsible for the care and maintenance of the U.S. Capitol and the buildings and grounds of the Capitol complex. The agency implements construction, renovation, conservation, and landscape improvement projects as authorized by the Congress.

The Architect of the Capitol is charged with operating and maintaining the buildings of the Capitol complex committed to his care by Congress. Permanent authority for the care and maintenance of the Capitol was established by the act of August 15, 1876 (40 U.S.C. 162, 163). The Architect's duties include the mechanical and structural maintenance of the Capitol, the conservation and care of works of art in the building under the Architect's jurisdiction, the upkeep and improvement of the Capitol grounds, and the arrangement of inaugural and other ceremonies held in the building or on the grounds.

In addition to the Capitol, the Architect is responsible for the upkeep of all of the congressional office buildings, the Library of Congress buildings, the U.S. Supreme Court building, the Thurgood Marshall Federal Judiciary Building, the Capitol Power Plant, the Capitol Police headquarters, and the Robert A. Taft Memorial. The Architect performs his duties in connection with the Senate side of the Capitol and the Senate office buildings subject to the approval of the Senate Committee on Rules and Administration. In matters of general policy in connection with the House office buildings, his activities are subject to the approval and direction of the House Office Building Commission. The Architect is under the direction of the Speaker in matters concerning the House side of the Capitol. He is subject to the oversight of the Committee on House Administration with respect to many administrative matters affecting operations on the House side of the Capitol complex. In addition, the Architect of the Capitol serves as the Acting Director of the U.S. Botanic Garden under the Joint Committee on the Library.