South of Nimes
The place has a train station
The historical centre is all contained within a compact area of the city walls, easily explored on foot.
Aigues Mortes is a nice fortified city, where it's possible to visit the ramparts, the walk through the village and the close by Salt Works.
Walk around the ramparts of the medieval city walls, and see inside the various towers, including the Constance Tower. This costs money. The ticket office, located in the North West corner, offers audio guides, but is closed at lunchtime.
Lots of shops selling tourist nick-nacks
There are many pleasant cafes and restaurants within the city walls, particularly around the central square.