The covering of the prayer hall consists of painted ceilings decorated with vegetal motifs and two domes: one raised at the beginning of the central nave and the other in front of the mihrab. The latter, which its cap is cut by 24 concave grooves radiating around the top, is based on ridged horns shaped shell and a drum pierced by eight circular windows which are inserted between sixteen niches grouped by two. The niches are covered with carved stone panels, finely adorned with characteristic geometric, vegetal and floral patterns of the Aghlabid decorative repertoire: shells, cusped arches, rosettes, vine-leaf, etc. From the outside, the dome of the mihrab is based on an octagonal drum with slightly concave sides, raised on a square base, decorated on each of its three southern, Easter and western faces with five flat-bottomed niches surmounted by five semi-circular arches, the niche in the middle is cut by a lobed oculus enrolled in a circular frame.