Next to the fishing port of Houmt Souk, the main town of Jerba, this imposing defensive monument was built in 1289 by Roger de Loria, admiral of Aragon and Sicily, on the site of a Roman fortification whose vestiges were reused in the construction of the fort. The latter was remodelled in the XVth century, reinforced in 1557 by Dragut and given its present configuration by a Spanish garrison of 6000 soldiers who came in 1560 to chase the Turkish pirates from the island before being exterminated in the same year by the Turkish pirate.

The borj is rectangular shaped and flanked by round and square towers. A drawbridge spanning a moat leads into the fort. The front door gives into a vestibule defending the access to the inner courtyard enclosing the vestiges of garrisons that have successively occupied the place since antiquity. An antiquarium has been fitted into one of the rooms and contains various objects found on the premises as well as explanatory panels. The wall walk provides a magnificent view over the surrounding area and the open sea.