Monastir was formerly called Ruspina, ( a corruption of the Punic name Rous Penna), and served ass Julius Ceasar's operations base for his African campaign. It was defended by a solid triple rampart, par of which still survives. Monastir became even more important in the VIIIth century when the Aghlabite dynasty of Kairouan built a Ribat, a sort of monastery which is both a place of mystic retreat and a military stronghold to defend the country against invaders arriving by sea.