• The Basilica Cistern (Cisterna Basilica, Yerebatan Sarayi)

Located 150 meters southwest of the Hagia Sophia, this 6th century impressive underground structure is the largest of hundreds ancient cisterns that lie beneath the city of Istanbul. It was called Basilica because it was located under a large public square where the Stoa Basilica stood.
The large and impressive Cistern provided a water filtration system for the Great Palace of Constantinople, to the Topkapi Palace, and to other buildings since the 15th century to modern times. The underground structure is 135 by 65 meters, capable of holding 80,000 cubic meters. The structure ceiling is supported by 9 meters high, 336 Marble and Granite columns, with Ionic and Corinthian style engraved capitals, and it takes 52 steps to descend to the Cistern entrance.
The water flew to the reservoir from the Eğrikapı Water Distribution Centre in the Belgrade Forest, 19 km north of the city. The Basilica Cistern has undergone several restorations in the 18th – 20th centuries period.

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The Basilica Cistern, or Yerebatan Sarayi, is an ancient underground water reservoir beneath Istanbul, Turkey

The Medusa Head Pillar in Basilica Cistern or Yerebatan Sarnici in wide angle view from below, Istanbul, Turkey