Sultanahmet

Many of the city's most famous buildings are in Sultanahmet, the center of old Istanbul. Once a church, then a mosque, and now a museum, the Hagia Sophia displays Byzantine mosaics. Six minarets mark the Blue Mosque, while walkways wind underground at the Basilica Cistern, which once supplied water to lavish Topkapı Palace nearby. Several museums border tranquil Gülhane Park, with its Bosphorus views.