The World Heritage site Pont du Gard has been around for a very long time with construction taking some 1000 people five years to complete the aqueduct to take around 5 million gallons of water per day the 50km to the city of Nīmes.
Although the waterway to Nīmes has long since gone, the aqueduct over the river Gardon remains a monument to the work carried out all those years ago. Amazingly, the water drops a mere 12m or so over all of that distance along which the water was carried via a stoned lined ditch covered with earth.
As this, of course, predated by a long way modern water purification methods, the local stones used to build the waterway were coated with mortar and lime to cut down on parisites, root invasion, etc.
Incidently, the bridge that you'll use to cross the river isn't anything like that old. It was constructed in 1743 as you can see from the extensive graffiti dating from that era. Unless you want to get a photograph of this bridge, the best time of day to see the aqueduct is in the early afternoon as you can see from the photograph here.
To make the most of your visit you should call in at the visitor centre housed in a modern complex just a short walk from the aqueduct itself. You'll find a few tourist shops, a tourist information centre and restaurant there.
With such a long period of human occupation of the site, there is lots of evidence of previous inhabitants in terms of ceramics and the like. The surrounding hills have numerous caves which are still being explored by archaeologists and therefore they aren't open to the public. Some of these caves are themselves listed as historic monuments including Balauziere, Salpźtriere and Sartanette.
Some 1.5 million people visit the site each year so it's best to avoid the peak Summer period if you can.
The nearest airport is Nimes which is served by discount airlines.
You can't easily reach the aqueduct by public transport so you'll need a car though there are lots of daytrip coach services from Nimes and other nearby towns.
