The El Djem Archaeological Museum sits a short walk south of the amphitheatre and holds one of the best collections of Roman mosaics in North Africa. The pieces were recovered from villa sites in and around the ancient city of Thysdrus, and the quality reflects how prosperous this region was during the height of the Roman empire — the surrounding plains produced enormous quantities of olive oil, and the wealth it generated went into extraordinary floors.
The mosaics are displayed in dedicated rooms around an open courtyard, and the subject matter runs from mythological scenes (Dionysus, Neptune, Medusa with her snake-hair rendered in meticulous tesserae) to hunting scenes, portraits, and domestic vignettes. The colours remain vivid despite nearly two millennia in the ground. Several pieces are large enough that the rooms were built around them rather than the other way around.
The museum is small enough to cover thoroughly in an hour or so. Combined with the amphitheatre — which is a few minutes' walk away — it fills a substantial half-day. Labels are in Arabic and French; some have English summaries. The garden around the courtyard contains sculptural fragments and architectural elements from the same excavations.