The Basilica Cistern, or Cisterna Basilica is the largest of several hundred ancient cisterns that lie beneath the city of Istanbul, Turkey. This subterranean structure was commissioned by Emperor Justinian and built in 532. The largest surviving Byzantine cistern in İstanbul, it was constructed using 336 columns, many of which were salvaged from ruined temples and feature fine carved capitals. It was originally known as the Basilica Cistern because it lay underneath the Stoa Basilica, one of the great squares on the first hill. Designed to service the Great Palace and surrounding buildings, it was able to store up to 80,000 cu metres of water delivered via 20km of aqueducts from a reservoir near the Black Sea, but was closed when the Byzantine emperors relocated from the Great Palace. The cistern was cleaned and renovated in 1985 by the İstanbul Metropolitan Municipality and opened to the public in 1987. I