Istanbul is Turkey's most populous city, and its cultural and financial center. Located on both sides of the Bosphorus, the narrow strait between the Black Sea and the Marmara Sea, Istanbul bridges Asia and Europe both literally and figuratively. Istanbul's population is variously estimated between 12 and 19 million people, making it also one of the largest cities in Europe. Istanbul was ranked third best city in Europe after Rome and ahead of Paris in the 2007 World's Best Cities rankings by Travel Leisure magazine. Istanbul is divided in three by the north-south Bosphorus Strait, the dividing line between Europe and Asia, the estuary of the Golden Horn bisecting the western part and the Sea of Marmara forming a boundary to the south. Most sights are concentrated in the old city on the peninsula of Sultanahmet, to the west of the Bosphorus between the Horn and the Sea. Across the Horn to the north are Galata, Beyollu and Taksim, the heart of modern Istanbul, while Uskudar is the major district on the comparatively less-visited Anatolian side of the city. The Black Sea forms the northern boundary of Istanbul. http://wikitravel.org/en/Istanbul