The Basilica Cistern, or Cisterna Basilica, is the largest of several hundred ancient cisterns that lie beneath the city of Istanbul, Turkey. The cistern, located 150 metres (490 ft) southwest of the Hagia Sophia on the historical peninsula of Sarayburnu, was built in the 6th century during the reign of Byzantine Emperor Justinian I. Today it is kept with little water, for public access inside the space.
This subterranean cistern, in Greek kinsterne, was called Basilica because it was located under a large public square on the First Hill of Constantinople, the Stoa Basilica. At this location, and prior to constructing the cistern, a great Basilica stood in its place, built between the 3rd and 4th centuries during the Early Roman Age as a commercial, legal and artistic centre.
Located in the northwest corner of the cistern, the bases of two columns reuse blocks carved with the visage of Medusa. The origin of the two heads is unknown, though it is thought that the heads were brought to the cistern after being removed from a building of the late Roman period.
- Wikipedia