One of Istanbul's magnificent historical constructions is the Basilica Cistern located on the south-west of Hagia Sophia. Built by the Byzantine emperor Justinian I. Justinian (527-565), this large underground cistern was named as the "Yerebatan Palace" among the public due to the marble columns rising from the water and seen as countless. When there is a Basilica in the place where the cistern is located, it is also known as the Basilica Cistern.

The cistern is a gigantic structure that covers a rectangular area of ​​140 meters in length and 70 meters in width. Covering a total area of ​​9.800 m2, this cistern has a water storage capacity of approximately 100.000 tons. There are 336 columns each of which is 9 meters high inside this cistern which is laid with a 52 step stone ladder. These columns, erected at intervals of 4.80 meters, bring 12 rows of columns, each containing 28 columns. It is understood that the majority of the columns are collected from the older structures, and a large part of the columns are marbled from various types of marble, consisting of one part and two parts. The titles of these columns, in places, have different properties. While 98 of them reflect Corint style, part of them reflect Dor style. The majority of the columns in the cistern, except for a few which are angular or grooved, are cylindrical. 8 columns in front of the northeastern wall towards the center of the cistern were exposed to the risk of fracture during a construction in 1955-1960, each of which was frozen in a thick layer of concrete and thus lost its former properties. The roof space of the cistern was transferred to the columns by means of arches. The brick-lined 4.80 m thick walls and brick paved floors were plastered with a thick layer of Khorasan, making them water-impermeable.

The Basilica Cistern, which occupied a large area in the Byzantine period and occupied the emperors' residence, meets the water requirement of the large palace and the other inhabitants of the region. The Basilica Cistern was used by the Ottomans for a while after the Ottoman conquest in 1453 and the gardens of the Topkapi Palace where the sultans sat.

It is understood that the Ottomans, who preferred the water in the place where the Islamic bases flowed instead of stagnant water for cleaning purposes, did not use it after building their own water facilities in the city. Until the middle of the 16th century it was noticed by the westerners until finally they came to Istanbul to investigate Byzantine remains in 1544-1550 It was rediscovered by the Dutch traveler P. Gyllius and introduced to the western world. P. Gyllius, in one of his investigations, traveled around the Hagia Sophia, where he learned from the large well-like large holes in the ground floors of the houses that his household members dug down and even held fish. A large underground cistern entered the cistern through a walled enclosed courtyard of a wooden building, a stone in the hands of a stepped stone stepping down into the ground. P. Gyllius, in very difficult conditions, walked around in the crotch chairs and picked up the measuring pads. Gyllius, whom he saw and traveled on his travels, influenced many travelers.

The cistern has passed through various repairs since its foundation. The first repair of the cistern, which was repaired twice in the Ottoman Empire period, was built by architect Kayseri Mehmet Aga at the time of Ahmet III (1723). The second reparation was made during the reign of Sultan Abdulhamid II (1876-1909). In the Republican Period, the cistern was opened in 1987 by being cleared by the Municipality of Istanbul and by making a trip platform. In May of 1994, again a large cleaning and maintenance passed.

Medusa Head

Two Medusa Heads, used as pedestals under two columns on the northwest corner of the cistern, are the masterpieces of the Roman sculpture art. It is not known which structures the Medusa heads were brought to and brought here, attracting the most attention of the people visiting the cistern. Researchers often think that cranes are being brought into use only as a column shade during construction. Despite this view, some legends about the Medusa Head have been formed.

According to one legend, Medusa is one of three Gorgona, the female monster of the underworld in Greek mythology. Medusa, the snaked head of these three sisters, has the power to turn his ministers into stones. According to one opinion, Gorgona paintings and sculptures were used to protect the great buildings and private places at that time, and the placement of the head of Sarnica Medusa was also a factor.

According to another custom, Medusa was a girl who boasted with black eyes, long hair and beautiful body. Medusa loved Zeus' son, Perseus. In the meantime, Athena liked Perseus and envied Medusa. So Athena turned Medusa's hair into a snake. Everyone Medusa looked at was now turning into a stone. Later, Perseus cut off Medusa's head and took advantage of this power to defeat many enemies.

Based on this, the Medusa Head was placed in swords in the Byzantine sword and placed opposite the column bases (for ministers to cut the stone). According to a custom, Medusa looked to the side and turned herself to stone. Therefore, the sculptor who made this sculpture made Medusa in three different places according to the reflection of the light.

This mysterious place, which is an integral part of the Istanbul excursion program, has so far been made up of former US President Bill Clinton to Dutch Prime Minister Wim Kok, former Italian Foreign Minister Lamberto Dini, former ex-Prime Minister Görans Persson and former Austrian Prime Minister Thomas Klestil so many people visited.

At present, one of the subsidiaries of Istanbul Metropolitan Municipality Kültür A.Ş. Yerebatan Cistern, which is run by the Museum, is home to many national and international events as well as being a museum.