The Tour Magne, or the Great Tower, is the only remnant of the ancient Augustan fortifications. Standing at the highest point of the city, Mont Cavalier, it overlooks the entire plain and is a focal point for all means of communication.

The tower was originally a dry-stone oval tower, with a maximum height of 18m and already part of a rampart.
A structure that was both prestigious and strategic, it represented sanctuary and protected the oppidum. By doubling its height and incorporating it into the town walls, Augustus demonstrated the new power of the colony of Nîmes over the “City” (in the territorial sense) of the Volcae. When the town’s population abandoned the higher ground, the Tour Magne nevertheless continued to play a military role. It was used to defend against the English during the Hundred Years’ War.