Istanbul is a unique city that straddles Europe and Asia and has served as the capital of two empires. It retains the historical, cultural, and commercial importance as the former capital of the Ottoman Empire. Major attractions include Topkapi Palace, once home to the Ottoman sultans, the Blue Mosque known for its blue Iznik tiles, Hagia Sophia which has witnessed over 1600 years of history, and the Grand Bazaar, a massive labyrinth of shops. Istanbul offers a blend of ancient and modern sites and architecture, reflecting its diverse history and the influence of multiple empires and religions.