A fascinating contrast of old and new, Istanbul is Turkey's largest city. Situated at the crossroads of Europe and Asia, Istanbul boasts some of the greatest examples of Byzantine art and architecture in the world. The Blue Mosque, completed in 1616, is one of the most famous religious buildings in the world. Visitors and Turks alike enjoy the Grand Bazaar, which features more than 4,000 street shops. (JASPER JULINEN—GETTY IMAGES)