Basilica Cistern

The Basilica Cistern (Βασιλική Κινστέρνα) is the largest underground cistern of Byzantine Constantinople. It was built under the Basilica located west of Hagia Sophia. Also known by its Turkish name Yerebatan Sarayı (“Sunken Palace”), it is one of the major tourist attractions of modern Istanbul. The Basilica Cistern, along with churches like Hagia Sophia, gives an impression of the massive construction projects once undertaken by Justinian I (527-565).

The Basilica Cistern is the only remaining structure of an important complex of buildings in the vicinity during Late Antique Constantinople. The cistern gets its name from the Basilica, often known as the Basilica Stoa or the Basilica of Illus, once located above it. Nothing is known about the site before Byzantium was inaugurated as Constantine’s capital. It was located west of the Augustaion and Hagia Sophia, and northwest of the Milion, the milestone at the beginning of the Mese. The Basilica, where Constantinople’s law courts were situated, was erected around the late 4th or early 5th century, with a large courtyard surrounded by four porticoes. Buildings attached to the Basilica included, the Library of Constantinople (said to contain 120,000 books in the 5th century) and the Octagon (the seat of a university where law courses were given and cases tried). Various stalls, including book sellers, were also located in the Basilica. The Basilica burned down in 476, after which it was rebuilt probably by Illus. It was again destroyed by fire in the Nika Riot of 532 during the reign of Justinian. The basilica was rebuilt by the prefect Longinus by 542, during which time the Basilica Cistern was built underneath it. Work probably began on the cistern in 527–28 and probably functioned some years before the Basilica was finished in 541. During the reign of Justin II a horologion, which was perhaps a sundial, was set up at the Basilica. The Octagon was reopened by Patriarch Sergius after being closed by Phocas (602-610), though it is permanently closed during Iconoclasm. It seems that the Basilica later served as quarters for craftsmen. Travelers to Constantinople, including Pierre Gilles in the 16th century, give accounts of the cistern. The cistern underwent repairs on several occasions during the Ottoman era. A section on its northwestern side was walled off, while eight columns on its eastern side were encased in concrete during construction work in the 1950s. In 1940, the cistern was handed over to the museum administration in order to prepare it for tourists.

The Basilica has a rectangular plan with beveled corners, measuring around 138 x 65 meters. Its capacity was around 80,000 cubic meters. Its vaults, which consist of bricks arranged in concentric squares up to its crown, are supported by 336 columns (12 rows of 28 columns that are around 9 meters high). The columns are around 9 meters tall and spaced 4.8 meters apart. It has plain impost capitals, as well 98 Corinthian capitals, which were perhaps in storage. Many of its shafts and plinths seem to have been reused. Its walls are lined with hydraulic plaster. The cistern was likely supplied by the Aqueduct of Hadrian which was restored by Justinian in 528. Procopius indicates that the cistern was built for the water shortages occurring during the summer (which is the dry season for the region). It, then, played a similar role to Binbirdirek Cistern, which was supplied by the Aqueduct of Valens.  It is unclear whether the cistern provided water to the public in the area or only to the nearby palace complex. While there were already massive open-air cisterns, this cistern probably provided cleaner water than the older open-air cisterns.

 The most notable examples of reused materials are the two columns decorated with Gorgon heads and the so-called “peacock-eyed” or “tear-drop” column. A similar Gorgon head, now at the Istanbul Archaeological Museums, was found at the Forum of Constantine, which suggests the two Gorgon heads of the Basilica Cistern might also originally decorated the Forum of Constantine.  The “peacock-eyed” column, which is similar to column fragments from the Forum of Theodosius, resembles the artistic convention of the Club of Hercules, as seen in the famous Farnese Hercules, which depicts Hercules resting on his club. This would mean that the column is decorated with knots of a tree, rather than peacock eyes or tear-drops. While the Gorgon head in particular have often been the source of speculation, it is unclear if the reused material had any particular significance.

Basilica Cistern.jpg
Basilica Cistern.jpg
Basilica Cistern.jpg

Description of the Basilica Cistern from De Aedificiis by Procopius

I shall now describe the labours which were carried out here by this Emperor to ensure an abundant water-supply. In the summer season the imperial city used to suffer from scarcity of water as a general thing, though at the other seasons it enjoyed a sufficiency.  Because that period always brings droughts, the springs, running less freely than at the other seasons, used to deliver through the conduits a less abundant flow of water to the city.  Wherefore the Emperor devised the following plan. At the Imperial Portico, where the lawyers and prosecutors prepare their cases, as well as all others who are concerned with such matters, there is a certain very large court (aulê), very long, and broad in proportion, surrounded by columns (peristylos) on the four sides (tetrapleuron), not set upon a foundation of earth by those who constructed it, but built upon living rock. Four colonnaded stoas surround the court, standing one on each side. Excavating to a great depth this court and one of the stoas (that which faces toward the south), the Emperor Justinian made a suitable storage reservoir for the summer season, to contain the water which had been wasted because of its very abundance during the other seasons. For receiving this overflow of the aqueduct  when its stream is spilling over, this cistern both furnishes a place for the water which for the moment can find no space, and provides a supply for those who need it when water becomes scarce. Thus the Emperor Justinian made provision that the people of Byzantium should not be in want of fresh water.

Photographs by William Earl Betsch From Dumbarton Oaks

Engraving by Johann Bernhard Fischer von Erlach (1721)

16th century description of the Basilica Cistern by Pierre Gilles

Through the Carelesness and Contempt of every thing that is curious in the Inhabitants, it was never discover’d, but by me, who was a Stranger among them, after a long and diligent Search after it. The whole Ground was built upon, which made it less suspected there was a Cistern there. The People had not the least Suspicion of it, although they daily drew their Water out of the Wells which were sunk into it. I went by Chance into a House, where there was a Descent into it, and went aboard a little Skiff. The Master of the House, after having lighted some Torches, rowing me here and there across, through the Pillars, which lay very deep in Water, I made a Discovery of it. He was very intent upon catching his Fish, with which the Cistern abounds, and spear’d some of them by the Light of the Torches. There is also a small Light which descends from the Mouth of the Well, and reflects upon the Water, where the Fish usually come for Air. This Cistern is three hundred and thirty six Foot long, a hundred and eighty two Foot broad, and two hundred and twenty four Roman Paces in Compass. The Roof, and Arches, and Sides, are all Brick-work, and cover’d with Terrass, which is not the least impair’d by Time. The Roof is supported with three hundred and thirty six Marble Pillars. The Space of Intercolumniation is twelve Foot. Each Pillar is above forty Foot nine Inches high. They stand lengthways in twelve Ranges, broad-ways in twenty eight. The Capitals of them are148 partly finish’d after the Corinthian Model, and part of them not finish’d. Over the Abacus of every Pillar is placed a large Stone, which seems to be another Abacus, and supports four Arches. There are abundance of Wells which fall into the Cistern. I have seen, when it was filling in the Winter-time, a large Stream of Water falling from a great Pipe with a mighty Noise, till the Pillars, up to the Middle of the Capitals, have been cover’d with Water. This Cistern stands Westward of the Church of St. Sophia, at the Distance of eighty Roman Paces from it.

Cosimo Comidas

Drawing by Cosimo Comidas (1794)


Drawing by W.H. Bartlett (1838)


Drawing by Thomas Allom (1836)

Plan by Müller-Wiener



​Bildlexikon zur Topographie Istanbuls: Byzantion, Konstantinupolis, Istanbul by Wolfgang Müller-Wiener

İstanbul'da Bizans Dönemi Sarnıçlarının Mimari Özellikleri ve Kentin Tarihsel Topografyasındaki Dağılımı by Kerim Altuğ

Die Byzantinischen Wasserbehalter von Konstantinopel by Forchheimer & Strzygowski

Two Romes: Rome and Constantinople in Late Antiquity edited by Lucy Grig and Gavin Kelly

Brickstamps of Constantinople by Jonathan Bardill

“The Infrastructure Of A Great City: Earth, Walls And Water In Late Antique Constantinople” by James Crow

“The Palace of Lausus and Nearby Monuments in Constantinople: A Topographical Study” by Jonathan Bardill

“A helping hand from the divine: Notes on the triumphalist iconography of the Theodosian dynasty” by Antti Lampinen

The Cambridge Ancient History, Volume 14 edited by Averil Cameron, Bryan Ward-Perkins, Michael Whitby

Oxford Dictionary of Byzantium edited by Alexander Kazhdan

De Aedificiis (Buildings) by Procopius (translated by H.B. Dewing)

The Antiquities of Constantinople by Pierre Gilles (translated by John Ball)


Basilica Cistern Album (Byzantine Legacy Flickr)

Basilica (Byzantine 1200)

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