Istanbul is the modern city historically known as Byzantium and Constantinople.
The settlement began as Byzantium, a Greek colony traditionally founded in the seventh century BCE. Roman Emperor Constantine the Great refounded it as Constantinople in 330 CE and made it the capital of the Eastern Roman, or Byzantine, Empire. Its position on the Bosporus gave it control of a crucial passage between the Black Sea and the Mediterranean and placed it at the meeting point of Europe and Asia.
Ottoman forces captured Constantinople in 1453 under Sultan Mehmed II, ending the Byzantine Empire. The city remained a major Ottoman capital until Ankara became the capital of the Republic of Turkey in 1923. “Istanbul” was used in Turkish before the modern republic, but the government standardized the name internationally in 1930. The city is still commonly described as transcontinental because its urban area extends across both sides of the Bosporus, although Ankara is Turkey’s political capital.