The Great Mosque was founded in 916 by the first Fatimid caliph, Abdullah al-Mahdi, and is one of the oldest mosques in North Africa. Its austerity is the point. There is no minaret, no decoration, just a vast white courtyard and a deep prayer hall — a deliberate statement against the showy religious architecture of Abbasid Baghdad.
Non-Muslims may enter the courtyard outside prayer times but not the prayer hall. The plain facade with its single arched gateway is the iconic image of Mahdia.