Leaving Perthir, we soon passed through the little village of Newcastle, which derives its name from a castle that may still be traced in an earthen mound 300 feet in circumference, and some intrenchments, but whose history no tradition reaches. This barrow, and an ancient oak of extraordinary size, are considered by the superstitious neighbourhood to be under the immediate protection of spirits and fairies, and to form the scene of their nocturnal revels. A spring near the village is deemed miraculous in the cure of rheumatic and other disorders.
Within a mile from this place we struck off the turnpike towards SCRENFRITH CASTLE, situated on the banks of the Monnow, in a sequestered spot environed by high hills. This fortress is of the simplest construction; its area, of a trapezium form, is merely surrounded by a curtain wall with circular towers covering each angle, and a demi-turret projecting from the middle of one side. Near the centre of the area is a juliet, or high round tower, upon a mound, which formed the keep, the door and window apertures of which are circularly arched; but the exterior walls of the castle appear to have been originally only furnished with oilets or chinks for shooting arrows through. Encumbered by the lowly habitations of a poor village, it has little claim to picturesque merit from most points of view; but on the opposite side of the Monnow, combined with a Gothic bridge of two arches crossing the stream, it forms a pleasing picture. Screnfrith Castle is allowed to be the oldest in Monmouthshire; it is certainly of British erection, and is probably of as remote antiquity as any in Wales.
Screnfrith, Grosmont, and White Castles, formerly defended the lordship of Overwent; which, extending from the Wye to the Usk, nearly comprised the whole northern portion of Monmouthshire. This tract of country, with its castles, fell into the hands of Brian Fitz Count, Earl of Hereford, who came over with the Conqueror; but soon deviated from his family, and was afterwards seized by Henry the Third, and conferred on his favourite Hubert de Burgh. Upon the disgrace of that virtuous and able minister, the capricious monarch granted the three castles to his son the Earl of Lancaster; and, with Caldecot castle, they still remain annexed to the dutchy.