El Djem was built, like almost all Roman settlements in Tunisia, on former Punic settlements.

The city is famous for its large 35,000 seater amphitheatre (only Rome's Colosseum with about 45,000 spectators and the ruined theatre of Capua are larger). The amphitheatre at El Djem was built by the Romans under proconsul Gordian, who was acclaimed Emperor at Thysdrus, around 238.

The amphitheater was used for filming scenes from the Monty Python film The Life of Brian (1979) and was also used for filming some of the scenes from Gladiator (2000).