During the 15th century, the engineers were obliged to envision a procession of new artillery. After numerous trials they hit on a new type of fortification wich rested on two major principles: the ramparts must be filled with earh and the curved bastions built without a dead angle. these two principles are perfectly illustrated in the Citadelle and Mont Alban.

The Citadel have been built to prevent every incomming from the sea: in 1543  war is on our shores, 110 Turkish galleys of the pirate Red Beard disembarked in the bay of Villefranche, burning and destroying everything on them way.

The victory of Saint Quentin (1557) and the treaty of Cateau Cambresis (1559) allow the duke of Savoy to send money to finish the construction of the citadel which will end in 1570. When the building of the citadel finishes, the manpower and the material moved to build the Mont Alban fort. This second construction considered as land defence comes in addition to Saint Elme fort, maritime defence.

Since the return of Savoy to France in 1860, the citadel was used as military quartering for the 24th Battalion of the Moutain Light Infantry. After 1945, the fortress is neglected. In 1965, the local council repurchases the citadel. The restoration of the building is undertaken in 1979. In 1981, the local council decided to install there the administrative center (town hall, police) and arts center (museums, auditorium, open air theater).