What's an aqueduct?
The aqueducts were bridges whose function was to transport water to places with no water. These aqueducts were connected to the sources leading to the city to which they corresponded. Most of an aqueduct's construction was underground, that is to say you could only see parts that go between mountains for example. These structures were normally contracted for great cities which were not supplied by either rivers or wells.
This image is of one of the best preserved aqueducts(Canaleta Massanella)