This underground cistern is the most impressive part of the Roman network of waterways built to supply Constantinople. 336 marble columns which rise 8 m. to support arches and domes lend a haunting, almost cathedral-like beauty and provide a cool, serene refuge from the bustle of city streets.

This massive structure, officially called the Sultan Ahmet Camii-the Mosque of Sultan Ahmet I, is studded with domes and surrounded by six minarets. Only after entering do you understand the name. The interior is decorated with 21,043 shimmering blue Iznik tiles and interspersed with 260 stained-glass windows, an airy arabesque pattern is painted on the ceiling.

This early version of a mall consists of a maze of 65 winding, covered streets crammed with 4,000 tiny shops, cafés, and restaurants. It is reputedly the largest number of stores under one roof anywhere in the world.

This chariot track was built in AD 203 by the Roman Emperor Septimus Severus on the model of the Circus Maximus in Rome. No stadium, ancient or modern, was ever so famous in its time, or played such an important role in its city’s public life. Much more went on here than just chariot races and the athletic events.

The greatest church in Christendom for more than a millennium with a huge dome, massive pillars, and magnificent wall mosaics, the 1,500-year-old Hagia Sophia is one of the most magnificent buildings ever constructed.

Istanbul's number one attraction sits on Seraglio Point, where the Bosphorus meets the Golden Horn and the Sea of Marmara. The heart of the Ottoman Istanbul for more than four centuries, this former imperial palace of the sultans holds priceless jewels, porcelain, paintings, costumes, royal armory and holy relics.