Project Description

There are hundreds of ancient cisterns hidden underneath the streets and houses of Istanbul. Of the two that are open to the public, the Basilica Cistern (Yerebatan Sarnıcı) is the largest and Istanbul’s most unusual tourist attraction.

The Basilica Cistern, or Cisterna Basilica (Turkish: Yerebatan Sarnıcı – “Subterranean Cistern”), is the largest of several hundred ancient cisterns that lie beneath the city of Istanbul (formerly Constantinople), Turkey. The cistern, located 150 metres (490 ft) southwest of the Hagia Sophia on the historical peninsula of Sarayburnu, was built in the 6th century during the reign of Byzantine Emperor Justinian I Today it is kept with little water, for public access inside the space.


This subterranean cistern, in Greek kinsterne (κινστέρνη), was called Basilica because it was located under a large public square on the First Hill of Constantinople, the Stoa Basilica. At this location, and prior to constructing the cistern, a great Basilica stood in its place, built between the 3rd and 4th centuries during the Early Roman Age as a commercial, legal and artistic centre. The basilica was reconstructed by Illus after a fire in 476.

 Ancient texts indicated that the basilica contained gardens, surrounded by a colonnade and facing the Hagia Sophia. According to ancient historians, Emperor Constantine built a structure that was later rebuilt and enlarged by Emperor Justinian after the Nika riots of 532, which devastated the city. Historical texts claim that 7,000 slaves were involved in the construction of the cistern.

The enlarged cistern provided a water filtration system for the Great Palace of Constantinople and other buildings on the First Hill, and continued to provide water to the Topkapı Palace after the Ottoman conquest in 1453 and into modern times.

Contrary to James Bond, who had to row his way through Istanbul underground cistern in From Russia with Love, you can take a stroll in the forest of hundreds of marble columns and enjoy the subterranean cool on a hot summer day.

* Basilica Cistern

 Underground Cathedral

The entrance to the Basilica Cistern of Istanbul is across the street from the Hagia Sophia. This immense underground water container was built during the reign of Emperor Justinian I in 532 to meet the water needs of the Great Palace. This marvelous piece of engineering only confirms yet again that those were the heydays of the Byzantine Empire.

The Basilica Cistern, which borrowed its name from the Ilius Basilica, is 143 meters long and 65 meters wide. The roof is supported by 336 marble columns, mostly in Ionic or Corinthian styles, each measuring 9 meters in length. Spaced at four-meter intervals, they are arranged in 12 rows of 28 columns each.

The cistern could hold 80.000 cubic meters of water, coming from the Eğrikapı Water Distribution Centre in the Belgrade Forest, 19 kilometers from the city. The water was transported to the city center via the 971-meter-long Valens Aqueduct (Bozdoğan Sukemeri) and the 11.545-meter-long Mağlova Aqueduct (Mağlova Sukemeri), which was built by Emperor Justinian I.

The cistern was forgotten for centuries and only accidentally rediscovered by the Frenchman Peter Gyllius in 1545. While researching Byzantine antiquities in the city, he noticed that people in the neighborhood not only got a hold of water by simply lowering buckets through holes in their basements, they miraculously sometimes even caught fish this way.


Visiting the Basilica Cistern

After cleaning and restoring the Basilica Cistern, the Istanbul Metropolitan Municipality opened it to the public in 1987. After descending into the underground water facility via a flight of stairs, visitors can take a stroll on the concrete walkways, enjoying the subdued lighting and the cool temperatures.

Make sure you walk all the way to the far left-hand corner of the cistern, to see the two Medusa heads. Both heads are casually used as column bases; one positioned upside down, the other tilted to the side. Both their positioning as their origin remain a mystery up till now, although rumor has it that they were recycled form an antique building of the late Roman period.


Medusa, a sea nymph, was the most beautiful of the three gorgon sisters. She was courted by Poseidon, and made love to him in a temple of Athena.

Furious, Athena transformed Medusa into a monstrous beast with snakes instead of hair, whose frightening face could turn onlookers to stone. She was beheaded while sleeping by the hero Perseus, who thereafter used her head as a weapon until giving it to the goddess Athena to place on her shield.

Having coupled with Poseidon previously, two beings sprang from her body when she was beheaded. One, Pegasus, was a winged horse later tamed by Bellerophon to help him kill the chimera. The other, Chrysaor of the Golden Sword, remains relatively unknown today.

In classical antiquity and today, the image of the head of Medusa finds expression in the evil-averting device.