Pont du Gard

A Roman aqueduct bridge built in the 1st century AD to carry water across the Gardon river to Nîmes. Its three tiers of arches stand 49 m high, making it the tallest Roman bridge in the world, and it's a UNESCO World Heritage Site. You can walk across the lower level, and there's a good museum on how the aqueduct was built.

In summer, bring a swimsuit: the river below has rocky beaches and deep, clear pools, and you can swim right under the bridge. A great way to arrive is by canoe: hire one at Collias, upstream, and paddle down through the gorge (about 2 hours). The site is also beautifully lit on summer evenings.

The entry fee includes parking and the museum. It's about 25 km from both Nîmes and Avignon, with buses from both towns.