Washington, D.C.-based Hartman-Cox Architects is known for its stately government and public buildings along the Pennsylvania Avenue corridor. This 8,000-square-foot house by founding partner Warren Cox, FAIA, however, is a tribute to modernist masters like Le Corbusier and Richard Neutra. Large expanses of horizontal windows wrap the custom house, which sits on a 2-acre landscaped and wooded site above the Potomac River in Maryland. A large deck and swimming pool link the main house with a 2-bedroom guest house. A tennis court lies just beyond.