İstanbul, the former Ottoman Capital
Interior of Hagia Sophia (from Greek: Ἁγία Σοφία, “Holy Wisdom”), a Greek Orthodox Christian patriarchal basilica, later an imperial mosque, and now a museum (Ayasofya Müzesi). From the date of its construction in 537, and until 1453, it served as an Orthodox cathedral and seat of the Patriarch of Constantinople, except between 1204 and 1261, when it was converted by the Fourth Crusaders to a Roman Catholic cathedral under the Latin Empire of Constantinople. It was a mosque from 29 May 1453 until 1931. The large shield displays the name of Umar, one of the most powerful and influential Muslim caliphs in history and a senior companion of the prophet Muhammad. The mosque was secularised and opened as a museum on 1 February 1935.