This Byzantine structure was commissioned by Emperor Justinian and built in 532. The Underground Basilica (also known as the Underground Cistern) is the largest, well-preserved cistern in Istanbul, constructed using 336 columns. According to historical texts, over 7,000 slaves were involved in its construction. Most of the columns were salvaged from ruined temples, featuring finely carved capitals. Its construction exhibits great symmetry and a grand conception. During summer days, the Underground Cistern would be a cool respite, offering a great retreat from the heat.

The Underground Basilica was designed to store up to 80,000 cubic meters of water and deliver it to the Great Palace of the Byzantine Empire and its surrounding buildings via 20 kilometers of aqueducts from a reservoir near the Black Sea. It is called the Basilica Cistern due to its location beneath the Stoa Basilica, which was one of the great squares located at the foot of the Seven Hills in Constantinople. After the relocation of the Byzantine emperors from the Great Palace, the Underground Cistern was forgotten by the city authorities until the time of the Conquest.

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In 1545, the scholar Petrus Gyllius rediscovered the Basilica Cistern. He had been researching Byzantine antiquities and had been told by local residents that they were able to get water by lowering buckets into a dark space beneath their basement floors and even sometimes catch freshwater fish. After conducting some research between the basements of the locals, Gyllius uncovered the main access to the cistern.

The Basilica Cistern has undergone several restorations since its discovery. The first two were conducted during the Ottoman Empire in the 18th century: the first during the reign of Ahmed III in 1723 by the architect Muhammad Agha from Kayseri, and the second in the 19th century during the reign of Sultan Abdulhamid II (1876–1909). In 1968, masonry and damaged columns were repaired, and finally, in 1985, the Underground Basilica was renovated by the Istanbul Metropolitan Municipality, and opened to the public in 1987.

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Maybe the most interesting highlight of the cistern is the two upside down Medusa heads located in the northwest corner. It is speculated that the heads were taken from a late Roman period building and moved to the basilica.Additionally, some people believe that their wishes will come true if they throw coins into the magical water surrounding the heads.

Nowadays, the Basilica Cistern is a popular tourist attraction and museum, with raised wooden platforms for visitors to explore. It has also become a venue for modern concerts and theatre plays that take place beneath its historical roof.


Visiting the Underground Cistern is a journey back in time that will leave you with unforgettable memories. With its 336 columns and two magical Medusa heads, the basilica is a sight to behold. Whether you’re a history enthusiast or just a traveler looking for a unique experience, the Underground Cistern is definitely something to add to your itinerary. At Tour Maker Turkey, we offer a variety of tours that will take you to the Underground Cistern and other nearby attractions.

Our experienced guides will give you insight into the history of the place and provide you with an opportunity to explore the Basilica Cistern in all its beauty. Our tour packages give you the chance to explore this unique place in the most efficient and informative way. What’s more, we also provide private tours for groups who want to visit the Underground Cistern in a more intimate setting. Our private tours provide flexible schedules and personalized experiences, allowing you to make the most of your time. Our tours are the perfect way to explore the Underground Cistern and its surrounding attractions.

Why not take the plunge and book one of our tours today? With our experienced guides and flexible tour packages, you will have the experience of a lifetime and make memories that will last forever!