Istanbul is Turkey's most populous city and its cultural and financial center. Located on both sides of the Bosporus, the narrow strait between the Black Sea and the Marmara Sea, Istanbul bridges Asia and Europe both literally and figuratively.

Founded by Constantine the Great on the site of ancient Byzantium, Istanbul (then Constantinople) was the capital, successively, of the Eastern Roman Empire (324-476), the Byzantine Empire (476-1453) and the Ottoman Empire (1453-1922). This almost unrivalled heritage, as well as its dynamic modern existence, makes Istanbul a fantastic destination for travelers of all stripes.

Most of Istanbul's sights are concentrated in the old city on the peninsula of Sultanahmet, to the west of the Bosporus. The foremost tourist attraction is the Hagia Sophia, originally a basilica constructed for the Byzantine Emperor Justinian. A masterwork of Byzantine engineering, its huge dome covers what was for over 1000 years the largest enclosed space in the world. Other must-visit destinations include: Topkapi Palace, the imperial enclave of the Ottoman emperors for three centuries; Sultanahmet Mosque, the "Blue Mosque" that still functions today; the Basilica Cistern, a giant underground cistern built by Justinian in 532; and the Hippodrome, the ancient center of Roman and Byzantine Constantinople.

While you're there, be sure to indulge in a visit to a hamam, or Turkish bath, and at least a few puffs of a narghile, or hookah.