The Tour Magne, or the Great Tower, is the only remnant of the ancient Augustan fortifications. Standing at the highest point of the Nïmes, 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.
References:The Amphitheatre of the Three Gauls was part of the federal sanctuary of the three Gauls dedicated to the cult of Rome and Augustus celebrated by the 60 Gallic tribes when they gathered at Lugdunum (Lyon). The amphitheatre was built at the foot of the La Croix-Rousse hill at what was then the confluence of the Rhône and Saône.
Excavations have revealed a basement of three elliptical walls linked by cross-walls and a channel surrounding the oval central arena. The arena was slightly sloped, with the building"s south part supported by a now-vanished vault. The arena"s dimensions are 67,6m by 42m. This phase of the amphitheatre housed games which accompanied the imperial cult, with its low capacity (1,800 seats) being enough for delegations from the 60 Gallic tribes.
The amphitheatre was expanded at the start of the 2nd century. Two galleries were added around the old amphitheatre, raising its width from 25 metres to 105 metres and its capacity to about 20,000 seats. In so doing it made it a building open to the whole population of Lugdunum and its environs.