The remains of some 75 amphitheaters have been located in widely scattered areas of the Roman Empire. The amphitheater in Caerleon is the best preserved example in Britain.
Known probably since the Middle Ages as King Arthur's Round Table, until 1926 it was a circular earthwork enclosing a deep hollow.
The first excavations were carried out by locals who dug trenches into the structure to recover stone for building purposes. The huge volume of Roman stone used in buildings in the village is evidence of such quarrying. Recycling started centuries ago.
Nowadays it is sometimes used for open air events and re-enactments. Entry is free (except for special events) and there is free parking right next to it.
Again, traveling off season means nobody is around. The downside is the rain and the mud. The ground was soaked and really muddy during our visit. Not a big deal for us, just something to keep in mind and pack good gear.