Located in the city of Istanbul, Turkey, the Basilica Cistern is an enormous underground chamber covering an area of over 9,800 square meters. This subterranean cistern was built during the 6th century within the reign of Byzantine Emperor Justinian I and is known to have been used to hold up to 80,000 cubic meters of water. Inside the chamber stands 336 marble columns that are thought to have been recycled from ruins of older buildings- a process called 'spoliation'. Even more exciting, the northwest corner holds the bases of two mysterious Medusa column blocks which were brought here after being removed from a building of the late Roman period. Today, the Basilica Cistern is opened to the public for visits that provide a truly unique experience.