In modern times, Constantinople is called Istanbul. The name "Istanbul" derives from a Greek phrase that means "into the city." The name was adopted by the Turkish-speaking Ottoman Empire and then by the Republic of Turkey.
The name "Constantinople" comes from the name "Constantine," who was an emperor of Rome. During the Byzantine era, Constantinople was the capital of the Byzantine Empire. The empire fell to the Turks in 1453, but the Turks continued to refer to it as Constantinople for many years. In fact, in the west, most people only began referring to the city as Istanbul after the establishment of the Republic of Turkey following World War I.