Arles is not a large city . . . I recommend staying in the city-center and walking everywhere. We stayed at a hotel (the three-star Hotel du Forum) in the Place du Forum (which I recommend). The Place du Forum is the site of the original Roman forum and bears no sign of it but it is filled with stately plane trees and has a couple of hotels and cafes. Leaving it, you will reach the Hotel de Ville just around the corner in the Place de la Republique.
The city hall is 17th century and is attractive, as is the Roman obelisk in the center of the square, but the site that you will want to see is the Eglise St-Trophime and its cloisters. We were hurried here as it was about to be closed for some reason, (and I would comment to my wife, as we left that I was pleased that we had been able to view the interior) but it is a fine 12th century church where Frederick Barbarossa was once crowned King of Arles. The style here is Romanesque with Gothic influences.
In the same block as the city hall, just down the Rue de la Republique, is the Musee d’Arlatan which is dedicated to the folklore of the region . . . we chose not to go, but if you need to see it, it’s only fifty paces away. On the opposite side of this block is the entry to the Cryptoporticus (Rue Balze), but it was closed on the day we visited… it is underground grain-storage and the surviving part of the old forum complex.
Now, on to the sites that people come to Arles to see . . . the Theatre Antique and Les Arenes (and this is a journey of only a couple of blocks). The theatre is guaranteed to disappoint. Built in the first century, it has been quarried and as a consequence, except for the two columns that remain intact, the rest is a jumble of stone. There are performances here in summer, and on the sunny March day on which we visited, a high school band was rehearsing for a performance. Les Arenes was also built in the first century and is remarkably intact. Seating 25,000, it is worth exploring, particularly for the views of Arles from the later, medieval tower. If you are in Arles in the summer, you might wish to consider attending a bull-fight here.
There are museums here, but unless you are to be here for a couple of days, you won’t have time to thoroughly explore them and the city at the same time. So resigned to our fate, it was back to the Place du Forum and the Café Van Gogh for dinner.