El Djem is a town in Mahdia
, population 18,302. It is home to some of the most impressive Roman remains in Africa
. The city was built, like almost all Roman settlements in Tunisia, on former Punic settlements. In a less arid climate than today's, Roman Thysdrus prospered especially in the 2nd century, when it became an important center of olive oil manufacturing for export. It was the seat of a Christian bishop - which is still occupied by a titular Roman Catholic bishop today.