The Almoravid fortifications were later destroyed and then rebuilt by the Almohad dynasty in the 12th century, under Caliph Muhammad al-Nasir.[2] The oldest sections of the walls today thus date back to this time.[3] These fortifications were restored and maintained by the Marinid dynasty from the 12th to 16th centuries, along with the founding of the royal citadel-city of Fes el-Jdid.[81] Construction of the new city's gates and towers sometimes employed the labour of Christian prisoners of war.[57]