El Djem or El Jem (Tunisian Arabic: الجمّ, il-Jām) is a town in Mahdia Governorate, Tunisia. Its population was 21,576 during the 2014 census. It is home to some of the most impressive Roman remains in Africa, particularly the world-famous "Amphitheater of El Jem".
The amphitheatre was built around 238 AD in Thysdrus, located in the Roman province of Africa Proconsularis in present-day El Djem, Tunisia. It is one of the best preserved Roman stone ruins in the world, and is unique in Africa. As other amphitheatres in the Roman Empire, it was built for spectator events, and it is one of the biggest amphitheatres in the world. The estimated capacity is 35,000, and the sizes of the big and the small axes are respectively 148 metres (486 ft) and 122 metres (400 ft). The amphitheatre is built of stone blocks, located on a flat ground, and is exceptionally well conserved.