 Eyüp, who died at the unsuccessful siege on Constantinople, provided a reminder that the Ottomans succeeded where earlier Islamic armies, led by a companion of the prophet, failed.According to UNESCO, Harar in eastern Ethiopia is "considered 'the fourth holy city' of Islam" with 82 mosques, three of which date from the 10th century and 102 shrines.The most important mosque in Kairouan (Tunisia) is the Great Mosque of Sidi-Uqba (Uqba ibn Nafi').