It is the oldest and most important of the defensive works erected along the Maghreb coast by Arab conquerors at the dawn of Islam. Founded in 796, this building underwent several renovations during the medieval period. Initially, in the shape of a quadrilateral, it is made up of four buildings opening onto two interior courtyards. In addition to the small cells of the “warrior monks” who, while carrying out their military functions, devoted themselves to prayer and contemplation, the Ribat houses two prayer rooms, the most spacious of which today houses rare cult collectibles. and medieval crafts. times. A hundred spiral steps provide access to the watchtower, from the top of which light messages are exchanged at night with the towers of neighboring ribats and which offers the visitor a superb view of the city of Monastir and its surroundings.