The Great Fatimid Mosque in Mahdia was built on a rocky outcrop in 916 during the reign of the Fatimid Caliph al-Mahdi, and there is nothing left of it that dates back to this period as it is except for the entrance porch and the northern gallery of the courtyard, while the rest of the building was reconstructed in the 1960s, and a portico The prominent entrance is from a pointed horseshoe arch, and the external facade of the mosque is carved with horseshoe arch niches on two floors separated by a mold, and in the lower part the niches are flat, while those in the upper section are flat in the back but semicircular at the top The Great Fatimid Mosque is the first example of a prominent balcony in Moorish religious architecture, reminiscent of the Roman era arches and the entrances to Umayyad castles.