Adjoining the fishing port of Houmt Souk, capital of the island of Djerba, this imposing defensive structure was built in 1289 by Roger de Loria, admiral of Aragon and Sicily, on the site of a square strong Roman whose remains were reused in the construction of the work. This was rearranged in the 15th century, reinforced in 1557 by Dragut and frozen in its current configuration by a Spanish garrison of 6,000 soldiers who came, in 1560, to drive the Turkish corsairs from the island, before being exterminated the same year by the Turkish corsair.
Rectangular in shape, the borj is flanked by round and square towers. It was accessed by a drawbridge over an insulating moat. The front door opens into a vestibule that defends access to the interior courtyard which contains the remains of the garrison which have succeeded one another in this enclosure since Antiquity. A room, converted into an antiquarium, accommodates various objects found on site as well as explanatory panels. The walkways, for their part, offer a superb view of the surroundings and the sea.