The Turkish name of the Basilica Cistern is Yerebatan Sarnıcı, which means sunken cistern.
Built in the 6th century during the reign of Emperor Justinian I, it is a larger chamber covering 9800 square meters 52 steps underground. Its ceiling is supported by 336 marble columns, each 9 meters high. It has a capacity to store 80,000 metric tons of water. But now it is covered by water only a few feet deep.