Basilica Cistern is one of the most fascinating historical structures in Istanbul which is located on the southwest side of Hagia Sophia. This large underground cistern was built under the order of Byzantine Emperor Justinian I (527-565) and named as “Yerebatan Sarayı” (which can be translated as “Palace Sinking Into Ground”) by the citizens of Istanbul because of its endless looking marble pillars rising from the water. It is also known as Basilica Cistern since there was a Basilica on the location of the cistern.
The cistern is 140 m long and 70 m wide, and covers a rectangular area as a giant structure. Accessible with 52-step staircase, the Cistern shelters 336 columns, each of which is 9 m high. Erected at 4.80 m intervals from one another the columns are composed of 12 rows, each has 28 columns. Majority of the columns, most of which are believed to be compiled from the ancient structures, are sculpted out of various kinds of marbles. The cistern has 4.80 m high brick walls, and the floor is covered by bricks, and plastered by a thick layer of brick dust mortar for water tightness. Covering an area of 9,800 square meters in total, the cistern has an estimated water storage capacity of 100,000 tons.
Two Medusa Heads, used as a base under two columns in the northwest corner of the cistern, are the masterpieces of Roman sculpture. It is not known from which structures are these Medusa heads taken from. Researchers generally believe that they were brought to the cistern during the construction phase in order to be used as the base of the columns.
The museum is open to visits seven days a week. Exceptionally, it opens at 13:00 on the first days of religious holidays and on January 1. The museum is open to visits between 09:00 and 18:30 every day. Entrance fee for foreign visitors is 20 Turkish Liras. Museums Cards are not valid at the Basilica Cistern as the institution is not affiliated with the Ministry of Culture.