The Kasbah of Sfax occupies the southwestern corner of the old city walls, a position that was strategically important for controlling both the land and sea approaches to the medina. The kasbah complex, built by the Aghlabids and modified in subsequent centuries, now houses the Sfax Archaeological Museum, which is worth a visit for its Roman mosaics, carved capitals, and objects recovered from the ancient city of Taparura that occupied this site before the Arab conquest.
The thick walls and towers of the kasbah can be walked around the outside, and the views from the adjacent ramparts give a good sense of how the old city's fortifications were organised. The neighbourhood around the kasbah, in the southwestern quarter of the medina, is quieter and more residential than the commercial centre.