Monnow Bridge - Credit: Wikimedia Commons
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 (Afon Mynwy) above its confluence with the River Wye. Read more on Wikipedia
Source: en.wikipedia.org