Istanbul is a major city in Turkey, located in Europe and Asia along the Bosphorus Strait. The Old City reflects the cultural influences of the various empires that ruled the region. In the Sultanahmet district, the Roman-era open-air Hippodrome was a chariot racing site for centuries, and Egyptian obelisks remain there as well. The iconic Byzantine Basilica Hagia Sophia has a soaring 6th-century dome and rare Christian mosaics.