David Lynn was a 21-year veteran of the Architect's staff before being appointed head of the office in 1923. He was an honorary member of the American Institute of Architects.

During Lynn's administration, four major buildings were added to the Capitol complex: the Longworth House Office Building, the Supreme Court Building, the Annex (Adams Building) of the Library of Congress, and the U.S. Botanic Garden Conservatory. In addition, the First Street wing of the Russell Building was built, the Capitol Power Plant was enlarged, and construction on the Dirksen Senate Office Building was begun. The Capitol Grounds were again expanded and underground parking for Senate employees was provided. Lynn also supervised a major remodeling of the House and Senate Chambers between 1949 and 1951.