Oxon Hill Manor is a neo-Georgian house of 49 rooms, located at Oxon Hill, Prince George's County, Maryland. It was designed in 1928 for Sumner Welles (1892-1961) by the Washington architect, Jules Henri de Sibour (1872-1938). It was built in 1929, and consists of a two-story main block of Flemish bond brick and a northern wing.