Monnow Bridge, in Monmouth, Wales, is the only remaining fortified river bridge in Great Britain with its gate tower standing on the bridge. Such bridge towers were common across Europe from medieval times, but many were destroyed due to urban expansion, diminishing defensive requirements and the increasing demands of traffic and trade. The historical and architectural importance of the bridge and its rarity are reflected in its status as a scheduled monument and a Grade I listed building. The bridge crosses the River Monnow 500 metres (1,600 ft) above its confluence with the River Wye.

Monmouth is a market town and community in Monmouthshire, Wales, situated on where the River Monnow joins the River Wye, two miles from the Wales–England border. The population in the 2011 census was 10,508, rising from 8,877 in 2001. Monmouth was the county town of historic Monmouthshire, although Abergavenny is the largest settlement and Monmouthshire County Council has its main offices at Rhadyr, just outside Usk. Monmouth is in the Monmouth UK Parliament and Senedd constituencies.