Today's city of Istanbul was known under many names of non-Turkish origin, as well as Turkish origin. One of the first names of this city is Constantinople, obtained by Emperor Constantine, who chose this city as his residence and enthused him for the capital of the Roman Empire. In addition, this city was also named Byzantium during the Byzantine rule, as well as Stamboul and Istanbul, how it was called from the time of the Turks. However, the name of the city was officially changed from Constantinople to Istanbul in 1930.
The correct answer is: Byzantium