El Jem is a small town in the east of Tunisia that holds the remains of a UNESCO World Heritage listed Roman amphitheater.
El Jem was formerly the Roman town of Thysdrus, one of the most important towns in North Africa after Carthage (now to be found in the suburbs of modern Tunis). The amphitheater was built around the middle of the third century AD and was thought to house up to 35,000 spectators.
Having fallen into some state of disrepair, its blocks being used for building the surrounding town and also contributing to the Great Mosque in Kairouan, the amphitheatre was declared a World Heritage site in 1979. More recently it has been used for filming some of the scenes from the Oscar winning film Gladiator.
El Jem is a small town and everything that may be of interest to the visitor can be reached on foot.
Train is also a very convenient method. The trains are comfortable and the travel is short. One would be able to take an early morning train from Tunis, see El Jem and take the afternoon train back to Tunis. All in a day and you would have some spare time to tool around in Tunis as well.
The amphitheater which dominates the modern town, and which was also featured in several scenes of the film Gladiator.
Also make the trip up to the Museum which is on the same entry ticket. As well as a large selection of mosaics and his has one restored Roman Villa, with all the mosaics in place and gives a real feel for their style of living. Adjoining this is the rest of this area of Roman Thysdrus, with the streets and floor plans laid out over a large area showing the variations to the house and villa plan.
Climb to the higher levels of the amphitheater and soak in the views over the surrounding countryside. Or, head down to the basement beneath the center of the arena and view the rooms where the animals for the fights would once would have been caged (this part is much more intact and accessible than the equivalent in Rome's colliseum).