Istanbul, founded in 657 B.C. as Byzantium, is an ancient transcontinental city. The historic city center lies in Europe, while a third of the city’s population of 14.4 million lives in Asia. Because of its unique location, it’s the largest city in both the Middle East and Europe. Located between the Sea of Marmara and the Black Sea, Istanbul straddles the Bosphorus Strait in Northwestern Turkey.