On the territory of the Medina of Sousse stands the fortress-like Great Mosque, built in 851, a few years after the founding of the city by the Aghlabids. The mosque was created in the image of the Sidi Okba mosque in Kairouan. After restoration work, the interior of the mosque was returned to its original appearance.

Initially, the mosque had two separate battle towers that guarded the entrance to the harbor. The domes on the minarets were completed much later. An unusual design feature of the mosque is the presence of an external staircase leading from the courtyard to the minarets. Equipped with loopholes, the walls of the courtyard of the mosque are decorated on three sides with high semicircular arches, the walls are decorated with a complex Kufi pattern. Prayer rooms, decorated around the perimeter with Roman columns, were built in the 9th century, then repeatedly rebuilt and expanded, and restored in 1964-65.