Following the Migration Period (Barbarian Invasions), the inhabitants of Saint-Saturnin-lès-Apt sought the safety of perched and fortified places. In 1009, a castrum was built on the rocky outcrop that dominates the current village. The first walled enclosure appeared in the 11th century, followed by a succession of ramparts at the end of the 13th century and the beginning of the 16th century. When the castrum became too small, the village spread outside the walls, abandoning the old castle of Saint-Saturnin-lès-Apt.