Guilford (gĭlˈfərd) [key], town (1990 pop. 19,848), New Haven co., S Conn., on Long Island Sound; founded 1639. Fishing, agriculture, and tourism are economically important. Guilford lies in an area that includes several summer shore communities. Some of the oldest houses in Conn. are there; the stone Whitfield House (1639–40), restored in 1936, is a state historical museum. Also of interest are the Hyland House (1660) and the Thomas Griswold House Museum (1735).