5 magnificent aqueducts of the ancient Roman Empire

An aqueduct is a channel or pipe used to transport water from a remote source to a desired location, such as a town, city, or agricultural area. The simplest, most primitive form of aqueduct was used in early Egypt, Assyria, and Babylon. It consisted of nothing more than an open canal dug between the river and the city where water moved by gravity alone. More complicated aqueducts were later developed in Persia (modern-day Iran), but it were the Romans who turned this necessity into spectacular architectures and engineering marvels that survive to this day.
The Romans constructed aqueducts to bring a constant flow of water into cities and towns, supplying public baths, fountains and private households. The aqueducts were built from a combination of stone, brick and the special volcanic cement pozzuolana. While the great archways leave a definite impression, the bulk of the Roman waterway system ran below ground. Channels bored through rock, or dug below the surface carried water where it was convenient and possible. Only where valleys or lowlands intervened, the conduit was carried on bridgework, or its contents fed into high-pressure lead, ceramic or stone pipes and siphoned across. Of the approximately 415 km in the aqueduct system present, only about 48 km consisted of the visible, mammoth arched structures.