A water supply, or navigable channel, constructed to convey water. It was built on gradually down hill surfaces, gravity was used to move the water. Usually used for communal drinking fountains.
Of approximately 260 miles in the aqueduct system, only 30 miles had the huge stone structures everything else was underground. Both Samos and Athens were supplied by long-distance aqueducts from the 6th century B.C. E. It was 2.5 km long and included the famous 1k tunnel designed by Eupalinus of Megara.