The Pont du Gard is actually a bridge and aqueduct over the Gard river built about 9c bce.   The Roman's original need was for an aqueduct to feed the city of Nimes.  These aqueducts carried water from about 31 miles away and may have been used until the 9th century.  Nime was a major Roman city with a coloseum and amphitheater.  It also holds a very well preserved Roman temple.