The Great Mosque is a typically austere Aghlabid affair. It was built, according to a Kufic (early Arabic) inscription in the courtyard, in the year AD 851 by a freed slave called Mudam, on the instructions of the Aghlabid ruler Abul Abbas. Mudam adapted an earlier kasbah (fort), which explains the mosque's turrets and crenulated wall, as well as its unusual location; the great mosque is usually sited in the centre of a medina.
The mosque is also unusual in that it has no minaret; its proximity to the ribat (fortified Islamic monastery) meant that the latter's tower could be used to call the faithful to prayer. The structure underwent 17th-century modifications and 20th-century restoration.
Non-Muslims aren't allowed beyond the courtyard but from there you can see the grand barrel-vaulted prayer hall.
