Basilica Cistern
Beneath the streets of Istanbul lies a vast underground hall with 336 columns standing in water. The cistern collected water for the imperial palace. In the dim light the room looks like a sunken church.
Constantinople lay on a peninsula with no springs of its own, and water had to be brought in by aqueducts and stored in cisterns. The largest covered cistern was built under the emperor Justinian in the 6th century, by tradition in 532, beneath a great basilica by the city’s main square. Hence the name. The cistern supplied the imperial palace and the buildings around it with water. It is about 140 metres long and 70 metres wide and could hold about 80,000 cubic metres of water.
The roof consists of brick vaults carried by 336 columns in twelve rows. Many columns and capitals were taken from older buildings and therefore differ: most are Ionic or Corinthian, a few Doric. The walls are built of brick with a thick layer of waterproof mortar. In the far north-west corner two columns stand on large stone Medusa heads, one laid on its side and the other upside down. They probably come from a Roman building, but nobody knows why they were placed like that.
In Ottoman times the cistern was almost forgotten, even though residents still drew water through holes in their cellar floors. The Dutch traveller Petrus Gyllius described in 1545 how he rowed among the columns by torchlight. The cistern was restored several times and opened as a museum in 1987, with walkways over the water. After a further restoration it reopened in 2022. The room shows how Byzantine builders reused ancient material and how even a purely utilitarian building could be given monumental form.