In Roman times Arles was the capital of Gaul, Spain and Britain. A city of such stature had an array of public buildings to match. The massive and imposing amphitheatre was built around 90 AD and held about 24,000 spectators. The circle is still intact and nowadays stages bullfights, often to Provencale rules where the bull is not killed, but also to Spanish rules, where it is.
Van Gogh spent two eventful years in Arles and painted a crowd watching a show at this amphitheatre.
More about Van Gogh in Arles here:
farewellvangogh.blogsome.com/