Istanbul has numerous cisterns which the Romans built. Emperor Justinian built the Basilica Cistern after the Nika Revolt in 532. Throughout the Roman period, the Basilica Cistern was used to provide water for the palace and the other buildings. After the Conquest, they used its water to water the garden of Topkapi Palace. The existence of the cistern was unknown, but it was rediscovered in 1546.
The Basilica Cistern is three hundred and thirty-six feet long, a hundred and eighty-two feet broad, and two hundred and twenty-four Roman paces in circumference. The roof, arches, and sides are all brickwork covered with terra-cotta, which is not the least impaired by time. Three hundred and thirty-six pillars support the roof.
In the far left corner of the cistern, at a slightly lower level, one o the columns mounted on ancient classical bases supported by Gorgons’ heads, one of them upside down and the other right side down. The Gorgons in Greek mythology were three sisters, one of whom Perseus slew Medusa.