Arles is in Provence in the southeast of France. Remote, uneventful, but definitely no waste of time, Arles is absolutely steeped in Provençal culture. The museums are small, but have some interested artifacts. Unfortunately there are no Van Goghs to be found in the city, despite the fact that his residence in Arles was his most productive era.
By train - SNCF Gare d'Arles.
By Bus - There are several bus lines from towns all over the Bouches-du-Rhône from which you can reach Arles. You can always buy your passage from the conductor.
By Car - Once again, you can Take the Autorout from Salon or yet another from Marseille, but give preference to the smaller routes and Alpilles towns like Fontvieille, Paradou, les baux, etc...
By foot/bike - I think it's the GR6, I'll check up on it.
The Roman arena (l'Arène d'Arles) is the main attraction here. You can wander through the same stone arches and passageways that were used in Roman days. Other sights include the Roman ruins, the marketplace, and a few museums.
Pastries from the small patissiers.
There is an Auberge de Jeunesse (youth hostel) at 20, avenue Foch. It's within walking distance of the train station. Another favored alternative is sleeping in the streets. Place de la libération offers a hospitable sidewalk with a bolder dedicated to two American WWII pilots shot down over Arles which you may sleep in the shelter of.