The Basilica Cistern is also known as the Sunken Palace or Yerebatansarayi in Turkish. It was built by Justinian and its main purpose was to provide water to the Byzantine palace. It is located under Istanbul and is the most important among many other cisterns; it was built in the Byzantine period, the size of this monument is almost 900 square kilometers, with a capacity of 800 cubic meters and it has 336 marble pillars of Doric or Corinthian style, 8 m high, placed in 12 rows of 28 columns each and at a distance of 4 m.
However, sixty columns on the southwest side were built and are no longer visible. The tank now has water at about 50 cm high. Imagine it filled to capacity. It has a capacity of 80,000 million cubes.
Much of the reservoir is made up of old or damaged buildings (mostly old Greek temples). Two columns on the northwest side rest on Greek bases, where massive Medusa faces are carved in relief.
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If you look behind the Cistern, you will see an upside down Medusa that many important people and investigators tried to find its meaning, but the closest theory they had, was that the upside down Medusa was to protect the water from evil spirits, but not very far from this Cistern there is another Medusa’s head in the opposite direction, so what it means nobody really knows.
This fantastic monument was forgotten in time but it was rediscovered by Petrus Gyllius who visited Byzantium in 1490 to find the monuments. Today the cistern is well maintained and has walkways and mood lights, you can even find a cafe on the place.
How to get there
It is located on Sultanahmed Square, northeast of the Hippodrome. Across the street from Hagia Sophia. You can visit it every day from 0:00 to 19:00, and you can spend half an hour to an hour there. The entrance ticket is : 190 TL (11 €)
http://yerebatansarnici.com/
Alemdar, Yerebatan Cd. 1/3, 34110 Fatih/İstanbul, Turkey
https://goo.gl/maps/bdApYc8ckhPNMLLy6