All improvements, alterations, additions, and repairs of the Capitol Building shall be made by the direction and under the supervision of the Architect of the Capitol.

(R.S. § 1816; Feb. 14, 1902, ch. 17, 32 Stat. 20; Mar. 3, 1921, ch. 124, 41 Stat. 1291; Oct. 31, 1951, ch. 654, § 3(15), 65 Stat. 708.)