istanbul-5 istanbul-5bis Beneath Istanbul lie hundreds of Byzantine cisterns, the largest of which is Yerebatan Saray Sarniçi, the Basilica Cistern (or Sunken Palace cistern). It is thought to have been built after the Nika revolt in 532 AD. After the conquest of the city by the Ottoman Turks, the cisterns were forgotten and were rediscovered in 1545.

There are 336 marble columns in the Basilica cistern, and the base of two columns is adorned with Medusa heads. Historians believe that the Medusa heads were used only because they were needed as pedestals for the columns in the construction of the Cistern. — Yerebatan Saray Sarniçi

According to our guide, when the Basilica cistern was built, they needed blocks to support some of the columns (hence, the Medusa heads). Some of these columns were taken from Ephesus. Christian Greeks built this cistern at the same time as the Hagia Sophia. They did not believe in “myths.”