The Roman town of Moridunum was the tribal capital of the Demetae and one of only two Roman civitates (chartered towns) in Wales — the other being Caerwent in the south-east. It covered roughly the area of the modern eastern town centre, but almost nothing survives above ground. The exception is the amphitheatre, which sits in a small grassed enclosure off Priory Street on the eastern edge of the town.
The amphitheatre is an earthwork rather than a stone structure, with a flat oval arena floor about 50 metres across, surrounded by sloping banks that originally carried wooden seating. It would have held around 5,000 spectators — substantial for a town the size of Roman Carmarthen. The site was excavated in the 1960s; very little fabric remains visible, but the shape of the arena is clearly readable and the perimeter banks are intact.
There is free public access at all reasonable hours. It is a 15-minute walk east of the town centre, just past Carmarthen Priory. Allow 15 minutes.