Second largest underground cistern in Istanbul after Basilica cistern. Located between Hippodrome and Forum of Constantine in Sultanahmet. Contains 224 columns, each 10 meters tall
Built by Emperor Justinian I in 532 as water reservoir for Great Palace. Measures 140 meters long, 70 meters wide, covering 9,800 square meters. Contains 336 well-preserved columns, each 9 meters high in twelve rows. Supplied water from Belgrad Forest in north
Built in 6th century by Emperor Justinian I as largest ancient cistern in Istanbul. Located beneath Sultanahmet streets, suspended by 336 9-metre columns. Used to store water for Byzantine and Ottoman Palaces. Rediscovered by French explorer Petrus Gyllius in 16th century