What lies beneath: Istanbul’s ancient water structures, the cisterns

Istanbul, where nature, history and culture combine to create a grand city, houses many churches, palaces, inns, mosques and baths that give the city its distinct character. 

One of the beauties that Istanbul has kept underground for centuries is its cisterns.

One of the most striking, and perhaps the most functional, examples of civil architecture, cisterns are among the most notable works that fall under the title of water structures.

In the past, cisterns were needed because there was no water infrastructure network as developed as today. Cisterns are underground water reservoirs created to collect water. 

For example, cisterns are built under the houses with canals that carry the water from the roof down, as well as giant cisterns like the cisterns of Istanbul.

Cisterns, carried by giant columns and having both visual and historical beauty, fulfilled an essential function in water storage in the past. The cisterns, both open and closed, ensured that the accumulated rainwater was used after being stored cleanly. Cisterns were used to store fresh water rather than salt water.

It is estimated that there are about 70 cisterns in Istanbul, although their exact number is not known. These 70 cisterns are thought to be from the Byzantine period. 

Massive structures such as the Serefiye Cistern and the Basilica Cistern are among the works that receive the most visitors in Istanbul. Other cistern structures such as Acimusluk Sokagı Cistern, Aspar Cistern, Binbirdirek Cistern, and Hagios Makios Cistern are among the most visited cisterns.

Since the cisterns are underground, they are built with a very strong foundation in terms of their load-bearing capacity and to minimise the risk of collapsing.

The cisterns are propped up by thick and strong columns. In the header sections of the columns, there are unique stone or marble engravings. The cisterns have water pools just below the column sections, that is, on their floors.

Stone or brick masonry is used on the wall sections of the cisterns, which are frequently encountered in Middle East countries. Supporting the carrying columns with arches adds a visual beauty to the cisterns, while at the same time making them stronger. The fact that water structures have a great place in Islam and the belief that they bring goodness also contributed to the increase in cistern structures in the Ottoman Period.

The Biggest in Istanbul: The Basilica Cistern

One of the magnificent ancient buildings of İstanbul is the Basilica Cistern located in the southwest of Ayasofya. Constructed for Justinianus I, the Byzantine Emperor (527-565), this big underground water reservoir is known as the “Yerebatan Cistern” among the public because of the underground marble columns. As there used to be a basilica in the place of the cistern, it is also called Basilica Cistern.

The cistern is 140 metres long and 70 metres wide, covering a rectangular area as a giant structure. Accessible with a 52-step staircase, the cistern shelters 336 columns, each of which is 9 metres high. Erected at 4.80 metre intervals from one another, the columns are composed of 12 rows, each having 28 columns. The columns convey the case-bay of the cistern through arches. 

A majority of the columns are known to have been compiled from other ancient structures and sculpted with various kinds of marbles. The heads of these columns bear different features in parts. 98 of them reflect the Corinthian style and part of them reflect the Dorian style. 

The cistern has 4.80 m high brick walls, and the floor is covered by bricks and plastered with a thick layer of brick dust mortar for water tightness. Covering 9,800 sqm area in total, the cistern has an estimated water storage capacity of 100,000 tons.