Istanbul historically known as Constantinople and Byzantium, is the most populous city in Turkey and the country's economic, cultural, and historic center. It is a transcontinental city in Eurasia, straddling the Bosphorus strait between the Sea of Marmara and the Black Sea. The city has been the site of human settlement founded by Thracian tribes between the 13th and 11th centuries BC. It was colonised by the Greeks in the 7th century BC and fell to the Roman Republic in 196 AD. The city was known as Byzantium until 330 AD, when it was renamed Constantinople and made the new capital of the Roman Empire. Constantinople was the capital of the Byzantine Empire, which ended with the Muslim conquest in 1453 AD. Constantinople then became the capital of the Ottoman Empire. Istanbul was inscribed as a UNESCO World Heritage Site in 1985.