The Biggest Basilica Cistern of Constantinople Re-opens

The biggest Byzantine Basilica Cistern in Constantinople opens its doors once again after five years of renovation. For a long time, it was an unknown construction to the Ottoman residents of the city.

By Dimosthenis Vasiloudis

The Basilica Cistern is one of the most magnificent byzantine underground structures of Constantinople, located southwest of Hagia Sofia. Following the completion of restoration on the Basilica Cistern, which began in 2017, its doors are now once again open to the public.

The underground basilica which hosted James Bond (Good Kisses from Russia) threatened to collapse at the slightest jolt, explains Aysen Kaya, deputy director of heritage at the municipality of Istanbul.

Renovation included earthquake strengthening and the changing of the lighting in the new museum, forming a new aesthetic which reveals the immensity of the places. Likewise, the refurbishment made it possible to protect this essential 1,500-year-old monument with the installation of a new footbridge. The previous walkway was fitted out for visitors at 1.60 meters above the ground to bring the stroll to less than 50 cm above the pavements. This would be made visible for the first time underwater.

It has been completely shut down since the coronavirus pandemic in 2020, allowing workers to strengthen and clean up the water palace. Steel rods were stretched across the cornices of the 336 columns holding up the subterranean ceiling and  arranged in twelve rows of twenty-eight. The pink brick walls have also been cleared of traces of past, less elegant renovation efforts.

New visitors can now enter into the mystical underworld water of Byzantine Μiddle Αges. Locally known as Yerebatan Saray (Turkish: underground palace) or Yerebatan Sarnıcı (Turkish: underground tank), The Basilica Cistern or Cisterna of Illus (Greek kinsterne=κινστέρνη), is the largest underground water tank built in the city, measuring approximately 141 × 66.5 meters in plan and with a capacity of 78,000 m3. It is located on the first hill of the city about 150 meters southwest of Hagia Sophia in the Sultanahmet area of the historic center.

It was part of a network of more than a hundred others begun by the early Eastern Romans. Because of its location under a large public square on the First Hill of Constantinople, the Stoa Basilica, it was named the Basilica. It was said to be built between the 3rd and 4th centuries, and if claims are to be believed, around seven thousand slaves were involved in the construction of the cistern.

The Basilica Cistern: A landmark of Byzantine engineering

The Stoa was probably built by Constantine the Great but was destroyed around 475. When the cistern was rebuilt around 542 by Emperor Justinian I after the period of the Nika Riots, it looked much as it does today. Its purpose was to supply water to Constantinople throughout the Byzantine period and to supply water to the adjacent Great Palace, where the Byzantine emperor was situated.

The cistern was one of Justinian’s most important public works and an excellent example of Byzantine engineering. The Greek historian Procopius of Caesarea described the cistern in his work ‘the Buildings’ in detail, noting that fresh water was brought into it by means of a conduit while a quantity of water was also stored there, which was usually abundant in seasons other than summer.

After the conquest of the city by the Ottomans, knowledge of the cistern seems to have been lost, but it was later discovered by Pierre Gilles (or Petrus Gyllius, 1490 – 1555) during his tour of Constantinople in the mid-16th century. Gilles describes how the residents had no knowledge of the reservoir’s existence despite the fact that they pumped water and caught fish by throwing buckets into the basements of their houses.

After the Fall of Constantinople, the water from the Royal Cistern was used in the irrigation of the gardens at the Topkapi Palace (Topkapi Sarayi). From the 18th to the middle of the 20th century, restoration works were carried out to preserve the cistern, which, after a renovation that began in 1985, had been open to the general public since 1987. It is one of the most important and oldest public spaces, and musical concerts are held in its space with excellent acoustics.

As part of restoration efforts which commenced in 2017, the ties fixing the columns to each other were renewed to support the structure during a possible earthquake. The entrance hall of the cistern was also redesigned while the lighting was renovated. The cistern now hosts visitors with an exhibition themed “light.”