General Post Office, now Tariff Commission Building, 1971
Credit: National Park Service
General Post Office (General Land Office): Built in two stages from 1839 to 1866, the building is the work of Robert Mills and Thomas U. Walter, two of the most noted 19th-century American architects.
This beautifully scaled and finely detailed building, with exceptionally fine interiors, is a tour de force of restrained neo-classical design and an outstanding example of American civil…