It shall be unlawful for any person to make any cut or trench in any highway, reservation, or public space in the District of Columbia, or to disturb or remove any public work or material therein, without a permit so to do from the Mayor of the District of Columbia. The person obtaining such a permit shall abide by all conditions and provisions of the permit; provided, that nothing in this section shall be construed to apply to public buildings of the United States, or to diminish the authority of the officer in charge of public buildings and grounds, or the Architect of the Capitol.