Ringwood, borough (1990 pop. 12,623), Passaic co., N N.J., in the Ramapo Mts. and on the Wanaque River near the N.Y. line. Iron was found nearby in 1730; mines and works were developed from 1764 by Peter Hasenclever, who made Ringwood Manor his headquarters. His successor, Robert Erskine, produced munitions for the patriots in the American Revolution. Other owners of the Ringwood properties included Peter Cooper and Abram S. Hewitt. Presented to the state in 1936, the estate (95 acres/38 hectares) became (1939) a park and the manor house was converted into a museum. Ringwood Manor has been designated a national historic landmark.