Chepstow Castle (or Castell Cas-gwent ni Welsh), located above cliffs on the River Wye, is the oldest surviving post-Roman stone fortification in Britain. Its construction began in 1067 under the instruction of the Norman Lord William FitzOsbern.
Chepstow was the southernmost of a chain of castles built in the Welsh Marches, and it was used in the conquest of Gwent. The speed with which William the Conqueror committed to the creation of a castle at Chepstow is testament to its strategic importance. The precipitous limestone cliffs beside the river afforded an excellent defensive location.
The castle is situated on a narrow ridge between the limestone river cliff and a valley. Even though it has four baileys, it is not a defensively strong castle, having neither a strong keep nor a concentric layout.
From the 14th century, the castle’s defensive importance declined. In 1682, the buildings were partly dismantled, leased to tenants and left to decay.