Glanum, an ancient hilltop fortified town, was founded by the Romans more than 2000 years ago and then abandoned in about 260 AD. Between Les Baux and St Remy it lay undiscovered until the 1920's, long after Van Gogh had painted his famous works on the hillsides above. Many visitors just look at the triumphal arches by the roadside, but you should cross the road and visit the museum before wandering around the excavated town. It had a hilltop dam nearby, still visible today, which provided water for the town. A visit to nearby St Remy and Les Baux will provide a good day in Provence.
The cafe/bistro on site provides good views of the old town, whilst providing authentic Roman fare !