Pont du Gard

No other ancient Roman sight in Provence rivals the Pont du Gard, a mighty, three-tiered aqueduct midway between Nîmes and Avignon—the highest bridge the Romans ever built. Erected some 2,000 years ago as part of a 48-km (30-mile) canal supplying water to Roman Nîmes, it is astonishingly well preserved. You can't walk across it anymore, but you can get close enough to see the amazing gigantic square blocks of stone (some weighing up to 6 tons) by traversing the 18th-century bridge built alongside it.