The nuns used to say Constantinople. They were sure it would be christianized again. Constantine was the Emperor who christianized the Roman Empire, and hence the West. They still held a grudge about the Crusades. Early Crusaders sacked Constantinople, not endearing themselves to locals. In 1453, the Turks conquered the city, driving out the Greek inhabitants, and converting St. Sophia to Hagia Sophia.
Vladimir Putin recently warned Erdogan to throttle back in Syria because Russia could take Constantinople in three days. Stay tuned.