The Great Mosque of Kairouan, built in 670 CE by Uqba ibn Nafi, predates the Dome of the Rock and ranks among Islam's oldest prayer halls still in continuous use. Its forest of 414 antique columns—salvaged from Carthaginian and Byzantine ruins—supports a hypostyle prayer hall that inspired every Maghrebi mosque that followed. Kairouan became North Africa's first Arab capital and the fourth holiest city in Islam, a pilgrimage destination when Mecca lay beyond reach. Seven visits to Kairouan, tradition holds, equal one hajj. Today the medina remains a working spiritual center. Artisans hammer copper in workshops unchanged since the Aghlabid dynasty, and the Zaouia of Sidi Sahab preserves the tomb of a companion of the Prophet. The city's ninth-century Aghlabid Basins, two monumental reservoirs fed by aqueduct, supplied a population of 100,000 in an age when few European cities surpassed 20,000. UNESCO inscribed Kairouan in 1988 for its role as a cultural and religious nexus that shaped the western Islamic world. Seventy kilometers east, the Amphitheatre of El Jem rises from flat Sahel farmland like a stone mirage. Completed around 238 CE under proconsul Gordian, it seated 35,000 spectators—more than the town's current population—and rivals the Colosseum in scale and preservation. Its three-story arcade of Corinthian columns stands nearly intact, the subterranean passages where gladiators and lions waited still navigable. The structure was never finished; Rome's third-century crisis halted construction, leaving toolmarks visible on unpolished blocks. In 1695, defenders used the amphitheatre as a fortress during the Kahina Revolt; Ottoman cannon fire breached the western wall, the only major damage in 1,800 years. El Jem's Archaeological Museum, housed in a French colonial villa adjacent to the amphitheatre, displays mosaics excavated from nearby Roman villas: hunting scenes, mythological panels, geometric patterns in tesserae so fine they approach painting. One mosaic depicts a procession of musicians and dancers celebrating Dionysus, the god's panther rendered in stone chips smaller than lentils. The museum's collection illustrates the wealth of Thysdrus, an olive-oil exporting city whose prosperity funded the amphitheatre and whose decline left it standing, too remote to quarry.