Monnow Bridge Gate is a late 13th century stone fortified two storey gate tower, founded by Henry of Lancaster. The gate stands on a three span stone bridge of 1272, which replaced a mid to late 12th century timber bridge. Defended on the Welsh side of the River Monnow, by the Clawdd Ddu rampart and ditch, the single arched passage originally had a portcullis in front of a pair of doors. In the 19th century, the gatehouse was pierced with pedestrian arches and the bridge was widened on both sides. A wall-walk with an encasing castellated parapet once crowned the upper storey but this was replaced by an attic and a hipped roof. This is now the only remaining example in Britain, where the gate actually stands on a medieval river bridge. Nearby is Monmouth Castle and 14 miles south-west is Usk Castle.