Basilica Cistern

The Basilica Cistern in Istanbul is an underground reservoir dating from the fourth to sixth centuries, located in Sultanahmet opposite Hagia Sophia. Begun under Constantine I and completed under Justinian, it stored water brought from the Belgrade Forest for use during drought or siege. After 1453 it supplied Topkapı Palace for a time, then fell into neglect until opening as a museum in 1987. Beneath an eight-metre vaulted ceiling stand 336 columns, many reused from ancient temples and differing in marble and workmanship. Two columns rest on carved Medusa heads, one upside down and the other turned sideways. Four-metre-thick walls of firebrick are coated with waterproof mortar, and the ceiling is faced with fired tiles. Today the water is no more than half a metre deep, and visitors walk along wooden platforms among reflections, lighting and installations including the “weeping column,” glass leaves and a dead tree.

Legend says the Medusa heads beneath the columns protected the Basilica Cistern, since the snake-haired Gorgon could turn anyone who looked at her to stone. One head was placed upside down, supposedly neutralising Medusa’s magical power. Ancient builders may have used the images as symbolic protection against evil spirits.