It was in the former town of Bobastro that Omar ibn Hafsen, a descendant of a Visigothic nobleman, established his headquarters. Here he brought together a group of rebels to protect the local inhabitants from the Ummayad Caliphate, before eventually embracing the Christian faith. All that remains today are the ruined walls of the alcázar (fortress), and an unfinished 10C church. Hewn out of the rock, the church has a basilical ground plan and is an unusual mixture of Roman, Visigothic and Muslim architectural influences.