You may notice ancient aqueducts snaking their way through Istanbul. These served as a water distribution channel for many years, until enemies tried to poison the water. Soon after, the Byzantines built large water cisterns underground to ensure fresh water supply to the populace. One of the largest is the Underground Cistern, which contains a large Medusa statue in its north-west corner. The cistern was re-built in 476 AD after the original was destroyed by fire. It can hold 100,000 tons of water.
