The main building of 's Herenelderen has been rebuilt in different periods. The oldest late Gothic style part is in the northwest corner and dates from the 16th century. The castle consists of three floors. The two brick building parts are built in Baroque style and date from the end of the 17th century. At the end of the 18th century, the courtyard was altered in the Louis XVI style.
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.