Old Patent Office - View this location on map Constructed in four sections over a 31 year period beginning in 1836, this is one of the largest Greek Revival buildings built by the U.S. government in the 19th century. Born of confused architectural parentage, this building nevertheless achieved a unity of design and boldly simple monumentality unsurpassed in American civil architecture. It now houses the National Portrait Gallery and National Museum of American Art. F and 9th St NW, Washington, District of Columbia Historical

---