D.C. Code § 6-1202
In order to promote the general welfare and to preserve and protect the places and areas of historic interest, exterior architectural features, and examples of the type of architecture used in the National Capital in its initial years, the Mayor of the District of Columbia, before issuing any permit for the construction, alteration, reconstruction, or razing of any building within said Georgetown district described in § 6-1201, shall refer the plans to the National Commission of Fine Arts for a report as to the exterior architectural features, height, appearance, color, and texture of the materials of exterior construction which is subject to public view from a public highway. The National Commission of Fine Arts shall report promptly to said Mayor of the District of Columbia its recommendations, including such changes, if any, as in the judgment of the Commission are necessary and desirable to preserve the historic value of said Georgetown district. The said Mayor shall take such actions as in his judgment are right and proper in the circumstances; provided, that, if the said Commission of Fine Arts fails to submit a report on such plans within 45 days, its approval thereof shall be assumed and a permit may be issued.
D.C. Code § 6-1202