MARSHFIELD, a parish, in the union and division of Newport, hundred of Wentlloog, county of Monmouth, 5 miles (S. W.) from Newport; containing 503 inhabitants. At Castleton, a hamlet in the parish, anciently stood a castle, occupied, if not built, by the Normans, to protect their conquest of Wentlloog: the only remains are some small ruins of the citadel, and the chapel converted into a barn. On the level summit of an adjoining hill is a circular encampment, called Pen-y-Park-Newydd. The living is a discharged vicarage, valued in the king's books at £6. 2. 6.; patrons and appropriators, the Dean and Chapter of Bristol. The great tithes have been commuted for £175, and the vicarial for £48; there is a glebe-house, and the vicar's glebe contains 27 acres. The church is a large and handsome structure, in the later English style.