Glanum started out as a Celtic fortified settlement (featuring a sacred well) dating back to appxox the 4th ntury BC for the earliest parts. It prospered again under the Romans in the 1st and 2nd centuries AD. The town part of the site was paid access only and we didn't go in.
What we did visit were two of the Roman contsructions on the other side of the road; France's oldest triumphal arch, built towards the end of Augustus Caesar's reign (so before 14 AD), which depicts the Roman victory over Gaul, and the Mausoleum of the Julii, dating to 40 BC.
The Mausoleum, which was probably a memorial rather than a burial place, is 18 metres (60 feet) high,