Article One of the United States Constitution
Congress has the exclusive right to legislate "in all cases whatsoever" for the nation's capital, the District of Columbia. Congress chooses to devolve some of such authority to the elected mayor and council of District of Columbia. Nevertheless, Congress remains free to enact any legislation for the District so long as constitutionally permissible, to overturn any legislation by the city government, and technically to revoke the city government at any time. Congress may also exercise such jurisdiction over land purchased from the states for the erection of forts and other buildings.