Istanbul is the largest city in Turkey, serving as the country's economic, cultural and historic hub. The city straddles the Bosporus Strait, lying in both Europe and Asia, and has a population of over 15 million residents, comprising 19% of the population of Turkey. Istanbul is the most populous European city and the world's 15th-largest city. The city was founded as Byzantium in the 7th century BCE by Greek settlers from Megara.