Features & Images » Travel

Istanbul's Basilica Cistern

An underground engineering marvel full of history and mystery



Modern-day Istanbul is an exotic cultural mix of east and west at the continental crossroads of Europe and Asia. Once known as Constantinople, the city evokes intrigue and wonder for its many architectural masterpieces such as Hagia Sophia and the Blue Mosque.

However, some are not quite as well known. About a stone's throw from the Hagia Sophia, the Basilica Cistern is an underground oasis with amazing architecture: It is an engineering feat for when it was built in 532 A.D. It can also be a cool, mysterious respite from the heat and sun of muggy Istanbul summer days. Today it is the largest surviving Byzantine cistern in Istanbul, despite centuries of conflict and siege, and even overall neglect.

All but forgotten by time, it wasn't until a French scholar named Pierre Gilles came to Constantinople in the mid 1500's that a forgotten relic would be rediscovered by the Western world. Gilles came to research Byzantine antiquities and was intrigued when he heard strange stories about locals retrieving buckets of fresh water through holes in their cellars. Some accounts even reported that fish were brought up from the mysterious underground waters. Adding to the mystery were the legends he heard of lost subterranean temples below.

Gilles set out to determine the source of the underground fresh water and in the process rediscovered the largest of the long-forgotten palatial cisterns from the Byzantine Empire. The subterranean palace even had freshwater fish that swam in a large hidden lake. Upon further investigation, he observed that the vaulted brick ceilings were supported by 336 nine-metre columns. The working theory was that marble columns were scavenged from nearby Roman ruins.


Emperors from the early Byzantine Period were known for building cisterns within the interior of the walled city. Not only did this meet the needs of the palace and its citizens, but it was also necessary during wars when sieges could cut off the city from outside water sources. Basilica Cistern was commissioned and built by the late Roman Emperor Justinian the Great in Constantinople. The year was 532 A.D.

Though designed to primarily support the Great Palace, it was constructed under a large public square on the first hill, the Stoa Basilica, after which it was appropriately named the Basilica Cistern. (It's also known as the "Sunken Palace" or "Yerebatan Sarayi" in Turkish language because of the underground marble columns.)

An interesting insight is that the cisterns were constructed as part of an overall rebuilding effort in Constantinople in the wake of the Nika Revolt in January of 532. Instigated by a hotly disputed chariot race, people revolted and took to burning much of the imperial city to the ground. Emperor Justinian responded by killing about 30,000 rioters and then by rebuilding the city.

Engineering Feat and Architectural Marvel

Some historical texts reference that as many as 7,000 slaves were used in constructing the cistern. In fact, one column in particular has engraved pictures that resemble eyes and tears that are tribute to the many hundreds of slaves who died while constructing the Basilica Cistern.

There are 52 steps leading from the surface to the underground reservoir below. Within the subterranean reservoir are the 336 marble columns that support the rectangular underground structure, spread in 12 vaulted rows. The ceiling gravity is supported by the columns through the use of arched cross vaults. Most columns are either in the Corinthian or Doric (Ionic) style, with many reputedly repurposed from ruined temples above.

With a length of 138 metres by 65 metres wide, and a storage capacity of up to 100,000 tons, the cistern was a remarkable engineering feat in not only grandeur, but also architectural symmetry.

Water was delivered via aqueducts from a reservoir near the Black Sea. However, after the Ottomans conquered Constantinople, they used the cistern waters to irrigate the gardens of Topkapi Palace. But when they installed their own system that they believed to be superior, the Cistern's waters were all but forgotten.

Restorations began in the mid 1980s by the Istanbul Metropolitan Municipality. They dredged the silted bottom, installed elevated walkways, added lighting, and built a cafe. By 1987 the Basilica Cistern was opened to the public.

Nowadays you walk along raised wooden platforms to admire the underground symmetry. Water still drips from the vaulted ceiling while the brick-domed ceiling provides acoustics for subdued classical music. Occasionally you may even see some of the carp swimming in the waters.

Medusa Mystery

One mystery remains: Why the presence of two Medusa heads positioned as pedestals for columns at the back of the cistern? Stranger is the fact that one of the two Medusa heads is upside-down. Not far from the upside-down Medusa the second head is oriented sideways.

There is a suggestion that the Medusas may have come from an older pagan temple, where Gorgon Medusa motifs were used as a protective force to ward off evil spirits in the Classical world. Essentially, they were apotropaic guardians of the cistern.

By way of mythical background, Gorgons were any of the three-winged sister monsters and the mortal Medusa who had hair of live snakes. Myth has it that they could turn people who looked at them into stone.

Some interpretations suggest that the heads were deliberately positioned this way to cancel out the power of the Gorgon's stare into stone. Others believe that the two faces — upside-down and sideways — were an intentional display of the power of the new Christian Empire. Still others think that if the two heads had the same orientation, that it would empower the snakes living on Medusa's head to radiate evil.

Nice to Know

Former President Bill Clinton visited the Basilica Cistern, as have several film directors. Dan Brown's novel Inferno was filmed in the cistern with the inverted Medusa pillar used prominently in the climax. Clive Cussler's 2010 book Crescent Dawn has a gun battle and escape scene at the cistern, while the 2009 movie The International filmed some vignettes in the cistern. Finally, who can forget the 1963 James Bond movie From Russia with Love, where the cistern was used as a location?

If you go

Basilica Cistern is located at the Sultanahmet square, on the right bank. A small building next to the tram line serves as the ticket office. Open from 9 a.m. to 6:30 p.m. mid-April to Sept., to 5:30 p.m. Nov. to mid-April. Admission is 20 Turkish lira or about CDN$9.