Founded by the Greeks of Sicily at the end of the 4thcentury BC, swiftly occupied by Carthage, the fortress of Kélibia was always integral if not dominant part of the urban landscape; built at the top of a rocky headland which dominates the sea on the north-eastern side of the Cape Bon, which explains its strategic scope and justifies its uninterrupted exploitation to the present. The history of the ancient city, called Aspis by the Greeks and translated by the Romans as Clipea, i.e. a shield, is closely linked to that of its citadel, which is rightly considered the emblem of the city and whose location determined the choice of the site and its urban development.
In its oldest parts, the citadel contains a Punic core. However, thanks to excavations and topographical surveys, scientists have managed to restitute the plans of its first foundation, in the 4th-3rd century BC, which show a more extensive, more fortified, pentagonal structure, perfectly adapted to the topography of the promontory on which it was built. Destroyed at the fall of Carthage in 146 BC, the structure was partially restored in the 6thcentury by the Byzantines, who erected a fortress that still stands in the middle of the borj. In the following century, the fortress was used as a refuge for the last troops fleeing the Arab conquerors to the nearby island of Pantelleria. This same fortress was transformed in the 8thcentury by the Muslims into a ribat, a kind of fortified observatory, occupied by ascetics all along the North African coast for the surveillance of the movements of the enemy Christian fleet coming from the other side of the Mediterranean. In the 11thcentury, the Normans of Sicily seized the rock, which was only recaptured in 1112 at the cost of a very deadly conflict. The Zirid prince Yahya, the architect of this victory, had the fortress rebuilt. The present layout and most of the structures date from this period. Afterwards, what happened to most of the fortresses of Tunisia happened to that of Kelibia, a diverse fortune: a mystical centre under the Hafsids, reinforcement of the defenses of the citadel in the 17th century, degradation and decline until the 19th century, when the French, masters of the country, provided the monument with a lighthouse and a maritime transmission centre.
With its surface area of about one and a half hectares, the fortress of Kelibia is one of the largest in the Islamic world. It is surrounded by a rubble stone curtain wall flanked by oblong towers. A single door on the Eastern sideleads into a straight corridor which leads towards a large square withat the centre water tanks dating from the Roman time and the vestiges of a mosque dating from the Aghlabidperiod.