The Romans were masters of the hydraulic art which they had learned from the Etruscans. Thanks to the invention of the arch, which allowed the construction of very long aqueducts, they brought it to the highest levels ever.

The water was used for the baths, fountains and sewers: when the aqueducts went out of use in late antiquity – due to lack of maintenance – the era of terrible medieval plagues began.

Before founding a city, the Romans established how to supply it with large quantities of water: they identified a suitable river or spring and built an aqueduct to carry the water it as far as they wanted.
The aqueduct was partly excavated in the rock, but when it was necessary to overcome valeys it passed over the arches of grandiose structures preserved in many Roman cities.

In Istanbul – the ancient Constantinople – there is still a large aqueduct which was planned by Constantine the Great when he made it the capital of the Empire; it was completed by the emperor Valens in 368 AD.
At its arrival point there are the remains of a "Water Tower", a structure that served to reduce its pressure before distributing it throughout the city. There were hundreds of cisterns with related distribution systems (castellum aquae).

In 532 AD – over 150 after its construction – the waters of the aqueduct were also conveyed to the large Basilica Cistern (Yerevatan Saray) which is located not far from the Water Tower.

It is one of the largest and most spectacular cisterns of the ancient world. It was built by Emperor Justinian I (527-565), who reused columns, marbles and other materials taken from the ancient Roman buildings which had then fallen into ruin. In fact, very little remains of the ancient city of Constantine.

The Basilica Cistern measures 140 x 70 meters and has a total of 336 columns about 9 meters high, with Doric or Corinthian capitals and shafts made of marble or granite. There are fragments of architraves which were shaped to transform them into columns.
Noteworthy are two large fragments of a relief with colossal heads of Medusa, on which other columns rest. You can see the monster's eyes and hair with snakes.