A Brief History of the Cistern of Theodosius in Istanbul

What is the Cistern of Theodosius?

The Cistern of Theodosius is one of the grandest elements of the incredible water storage system that supplied Constantinople with fresh water throughout its history.

Cistern of Theodosius History

If you’ve already visited the Aqueduct of Valens and the Basilica Cistern, you will know that the city of Constantinople had something of a fresh-water problem. In the 2nd century, the Roman Emperor Hadrian had built an aqueduct to supply the much smaller city of Byzantium and in the 4th century the Emperor Valens had built his own astonishing aqueduct with its 268-kilometre network of water channels. But the problem in Constantinople was not only in bringing fresh water to the parched city; in summer, the springs that supplied the city dwindled, or worse dried up, and so in the sweltering heat, the citizens of the capital would endure periodic punishing droughts.

It wouldn’t be an exaggeration to call Constantinople a city of cisterns. The Basilica Cistern and the Cistern of Theodosius are both part of a vast underground network: archaeologists have uncovered more than 200 Byzantine cisterns; a number that far outstrips any other ancient or medieval city. The huge population of Byzantine Constantinople, and the poverty of its natural water supplies, demanded a complex system of storage and management of water resources which would be unmatched until the industrial revolution.

Even among the many cisterns of Constantinople, this one is extraordinary. The cistern is 45 by 25 metres, and the roof is supported by a forest of enormous marble columns. It’s a beautiful, as well as a practical space, and says something about the nature of imperial munificence that this kind of expense and effort was expended on a cistern, when it could have been directed at another palace or cathedral. The Cistern of Theodosius is not as well documented in the historical record as the Basilica Cistern. Archaeologists are fairly confident in dating it to the 5th century and it could well be contemporary with Theodosius’s other great public building project, the famous Walls of Constantinople. Between them, the walls and the water system, Constantinople would remain impregnable to siege for more than a millennium.