Istanbul, formerly Constantinople, is the largest city of Turkey. It was the capital until 1923, when Kemal Ataturk moved that to Ankara. It is located at the Bosporus Strait, straddling Asia and Europe.
The first settlements were perhaps 3000 years ago. In the seventh century BCE, Greeks settled it as Byzantium, which became part of the Roman Empire. In 306 CE, Emperor Constantine the Great made it capital of the Eastern Roman Empire, and it became known as Constantinople. It was conquered in 1453 by the Ottoman Turks, and became the third and final capital of the Ottoman Empire.