Did you know Istanbul once had one of the world’s largest ancient water systems?

Constantinople, today’s Istanbul, depended on a well-functioning water supply system even in ancient times. Lacking nearby rivers, the Byzantine capital developed one of the most complex hydraulic systems of its time starting in the 4th century AD.

An ingenious network of aqueducts and cisterns

Constantinople’s water supply system consisted of kilometer-long aqueducts, open channels, underground pipes, and large storage cisterns. Its primary goal was to ensure a steady supply of fresh water to the city—even during sieges—a crucial factor in the city’s resilience over the centuries.

The Basilica Cistern: An underground masterpiece

The most famous structure of this system is the Basilica Cistern (Yerebatan Sarnıcı). Covering an area of about 9,800 square meters, supported by 336 Corinthian marble columns, and capable of holding over 80,000 cubic meters of water, it remains a technical and architectural marvel to this day.

In addition to the Basilica Cistern, numerous other reservoirs were built. More than 100 cisterns have been historically documented.

These systems supplied not only palaces and baths but also public fountains, ensuring the survival of the population during times of crisis.

A historical legacy to experience

Many parts of the Byzantine water supply system are still preserved today and open to visitors. The Basilica Cistern is among the most visited landmarks in Istanbul.