Istanbul is a world center of great importance in the past and present. The city embraces Asia on the one hand and Europe on the other. 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 physically and culturally. With its historical peninsula, numerous scenic and historical sites, Istanbul is a magnificently unique city that has been the capital to many civilizations from past to present and still continues to be home to residents from all over the world. Istanbul's population is estimated between 12 and 19 million, making it one of the largest cities in Europe and the world.
Expanding the ancient Greek colony of Byzantium by the order of the Roman Emperor Constantine the Great, the imperial city of Constantinople for nearly a thousand years was the last remaining outpost of the Roman Empire. It was finally conquered by the Ottoman Sultan Mehmed II in 1453, an event sometimes used to mark the end of the Middle Ages. By the mid 1500s, Istanbul, with a population of almost half a million, was a major cultural, political, and commercial center. Ottoman rule continued until it was defeated in WWI and Istanbul was occupied by the allied forces. When the Republic of Turkey was born in 1923 after the War of Independence, Kemal Atatürk moved its capital to the city of Ankara. However, Istanbul has continued to expand dramatically; today its population is approximately 14 million. It continues to be a city that creates its own history at the intersection where both continents meet.
Istanbul is divided in three parts by the north-south Bosphorus Strait , 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. The Grand Bazaar will enchant you with its bright and pleasant environment and the famous Hagia Sophia mosque exudes a sense of peace. A tour of the pearl of the Bosporus, Ortaköy, will let you enjoy the delightful views along the deep blue coast. Across the Horn to the north are Galata, Beyoğlu and Taksim, the heart of modern Istanbul, while Kadıköy is the major district on the comparatively less-visited Anatolian side of the city. The Black Sea forms the northern boundary of Istanbul.