Château de Plain-Marais was built to the hill surrounded by marsh land in the 14th century. In the 15th century it was owned by Jean d'Arclais and later by Jean de Talbot. It was originally a square stone castle surrounded by a moat. Current main building, annexes and tower were built in the 15th and 16th centuries and the major restoration was made in the 17th century.References:
Built around AD 90 to entertain the legionaries stationed at the fort of Caerleon (Isca), the impressive amphitheatre was the Roman equivalent of today’s multiplex cinema. Wooden benches provided seating for up to 6,000 spectators, who would gather to watch bloodthirsty displays featuring gladiatorial combat and exotic wild animals.
Long after the Romans left, the amphitheatre took on a new life in Arthurian legend. Geoffrey of Monmouth, the somewhat imaginative 12th-century scholar, wrote in his History of the Kings of Britain that Arthur was crowned in Caerleon and that the ruined amphitheatre was actually the remains of King Arthur’s Round Table.
Today it is the most complete Roman amphitheatre in Britain.