Cirencester was an extremely important town in Roman times (known then as Corinium) and an excellent example of Roman remains can be found at Cirencester Amphitheatre on the west side of town. The excavation there shows the amphitheatre to be one of the largest and best-preserved in Britain.

Archaeologists have dated the building of the site at around the early part of the second century, possibly built upon an existing Roman quarry. The amphitheatre now survives as an oval earthwork with some arena entrances still visible. There remain two curving mounds or seating banks, measuring up to thirty metres in width, surrounding a central area of earth, measuring 49 metres by 41 metres that it is believed would have been used for entertainment purposes.
The amphitheatre is estimated to have had a seating capacity for approximately eight thousand spectators. The mounds would have been covered with planks and dry-stone walling in order to support the wooden seats that spectators would have used. It is believed that renovations may have taken place in the later part of the second century when the arena may have been enclosed by a high stone wall, plastered and painted to look like marble.

The sort of entertainment that would have taken place in the amphitheatre in Roman times would probably have included violent and bloodthirsty sports such as gladiatorial battles, cock fighting and bear baiting.

Locally, the amphitheatre is known as The Bull Ring. This name is thought to have its origins in the eighteenth century when the theatre was used for bull-baiting contests. Other uses for the amphitheatre may have included use as a market in the third or fourth century and as a fortified retreat in the fifth or sixth century.