The Great Mosque of Al Qala’a (مسجد القلعة) is a major historical Mosque located in the UNESCO World Heritage city of Qal’at Bani Hammad, in the province of M’sila, Algeria. Its construction dates back to the early 11th century, during the rule of the Hammadid Emir Hammad ibn Buluggin.

The Mosque spans an area of over 3500 square meters (38,000 sq ft), taking on a rectangular layout.[4] It encompasses a vast courtyard, a hypostyle prayer hall, and a square minaret towering at 25 meters (82 ft) in height.[5][6] Regarded as one of the largest historic mosques in Algeria, second only to the Mansourah, it also contains one of the country’s oldest minarets.[7][8][9] Additionally, the mosque likely exerted an influence on subsequent Almohad minarets, notably the Giralda in Seville.[10][11] Together with other archaeological remnants of palatial structures, it stands as a primary testament to the opulence and impact of the Hammadid civilization.[9][12]

Unfortunately, practically all of the buildings that can be seen at the Qalat Bani Hammad today only exist as the foundations of destroyed buildings without roofs. The minaret of the large mosque in the qalat is the only construction that has survived above ground level beyond the remains of a plan. A masonry building, the minaret is made of stone bricks set in a coursed ashlar design. The minaret’s square design is reminiscent of examples from Andalusia, but the exterior’s arrangement of arches is most likely a Fatimid Egyptian influence.

The mosque is quite big, with a rectangular layout that is 64 meters long from north to south and 56 meters broad from east to west. The mosque’s longitudinal axis is parallel to the meridian running from north to south. Public entrances are found in the east and west walls, which lead onto the mosque courtyard, and a minaret is situated in the middle of the north wall.

The vast sahn, which is surrounded by arcaded galleries, leads to the hypostyle prayer hall, which is split into a grid that is thirteen aisles wide and eight bays deep by columns. The mosque had a sizable maqsura that was now gone; it was located in front of the qibla niche on the south wall and was five bays wide and four bays deep. If it weren’t currently totally destroyed, the Qalat Beni Hammad mosque would be one of the biggest in all of Algeria.