The Church of the Holy Wisdom, known as Hagia Sophia (Άγια Σοφία) in Greek, Sancta Sophia in Latin, and Ayasofya or Aya Sofya in Turkish, is a former Byzantine church and former Ottoman mosque. Now a museum, Hagia Sophia is universally acknowledged as one of the great buildings of the world.
Address: Aya Sofya Sq., Sultanahmet, Istanbul
Telephone number: (+90) 212 522 1750
Opening hours: Tues-Sun 0900-1700 (winter); Tues-Sun 0900-1800 (summer) plus first Monday of every month.