Istanbul (/ˌɪstænˈbʊl/ IST-an-BUUL, US also /ˈɪstænbʊl/ IST-an-buul; Turkish: İstanbul [isˈtanbuɫ]), formerly known as Constantinople, is the largest city in Turkey and the country's economic, cultural and historic center. The city straddles the Bosporus strait, and lies in both Europe and Asia, with a population of over 15 million residents, comprising 19% of the population of Turkey. Founded as Byzantion by Megarian colonists in the 7th century BCE, and renamed by Constantine the Great first as New Rome (Nova Roma) during the official dedication of the city as the new Roman capital in 330 CE, which he soon afterwards changed to Constantinople (Constantinopolis), the city grew in size and influence, becoming a beacon of the Silk Road and one of the most important cities in history. It served as an imperial capital for almost sixteen centuries, during the Roman/Byzantine (330–1204), Latin (1204–1261), Byzantine (1261–1453), and Ottoman (1453–1922) empires. The city was instrumental in the advancement of Ankara replaced the city as the capital of the newly formed Republic of Turkey. Istanbul is home to several UNESCO World Heritage Sites.