The walls are 40 centimetres (16 in) thick. Nine doors lead into the interior of the building, where the many pillars and arches create a spacious, light, cool and calm environment.[1] Beside the mihrab there is a recessed niche for the minbar, where the prayer leader stands. Mosques in Arabia and East Africa have similar minbar niches, which may indicate that the mosque builders followed the Ibadi school of Islam.[11]