The site of Glanum is just south of St.-Rémy-de-Provence on the northern flank of les Alpilles. Even though there was a small fee to pay, we parked and paid and wandered around among the stones. From what I read, a spring issued from the ground in the foothills at this location and the Celto-Ligurian people associated it with healing. The Greeks then came and took over, building their town on the site in the third and second centuries before our era.
The Romans invaded in the second century and occupied the town. Later, under Augustus in the first century of our era, the Romans razed practically everything and rebuilt the town in the classic Roman style.
A partially reconstructed temple near the forum - I think that the white stone is meant to differentiate the reconstruction from the original state of the site.
Around the third century of our era, Germanic invasions forced the city's residents to flee and it was abandoned. The canals built to supply the town silted up and sediment washed down from the neighboring mountains slowly covered up the ruins.
Archaeologists have been working to uncover the ruined city since the early 1920's.