This mosque, which neighbors Médersa Ben Youssef and Qoubba Ba'adiyn, is the oldest and also the second biggest one of the medina, after the Koutoubia Mosque. Its minaret is more than 130 feet high. The mosque was built by Sultan Ali Ben Youssef (1106-1142), and partially or mostly destroyed and rebuilt a few times since then. Its present version dates from the 19th century. It is not open to non-Muslims.