What Roman amphitheatre in Tunisia is the largest surviving amphitheatre outside Italy?

The Roman amphitheatre in Tunisia that is the largest surviving amphitheatre outside Italy is the Amphitheatre of El Jem.

Built around AD 238 at the Roman city of Thysdrus, modern El Djem, the monument is one of the most impressive survivals of Roman Africa. It was constructed on level ground as a free-standing structure, rather than being cut into a hillside. Its three tiers of arcades and enormous oval plan were modelled in part on the Colosseum.

The amphitheatre measures about 148 by 122 metres and could accommodate an estimated 35,000 spectators. Its arena, podium wall, underground passages and much of the seating infrastructure remain unusually well preserved. Thysdrus prospered through trade and olive-oil production, helping explain why a provincial city could support such an ambitious entertainment complex. The building is sometimes called a “colosseum,” but that is a descriptive comparison, not its formal name. UNESCO added it to the World Heritage List in 1979.