The Architect of the Capitol is responsible to the United States Congress for the maintenance, operation, development, and preservation of the United States Capitol Complex, which includes the Capitol, the congressional office buildings, the Library of Congress buildings, the United States Supreme Court building, the United States Botanic Garden, the Capitol Power Plant, and other facilities.
Until 1989 the position of Architect of the Capitol was filled by appointment from the President of the United States for an indefinite term. Legislation enacted in 1989 provides that the Architect is to be appointed for a term of ten years by the President, with the advice and consent of the United States Senate, from a list of three candidates recommended by a congressional commission. Upon confirmation by the Senate, the Architect becomes an official of the Legislative Branch as an officer and agent of Congress; he is eligible for reappointment after completion of his term.
References
http://www.aoc.gov/, a public-domain publication of the Architect of the Capitol