When Augustodunum was founded in the 1st century B.C., the city was endowed with a 6 km long rampart with 4 gates, two of which remain today. The best preserved part is located on boulevard Mac-Mahon.
Built around 70 AD and located east of the ancient city, it was intended for dramatic performances. With its 148m diameter, it appears as the largest in the Roman world, able to accommodate 20,000 spectators. The theater was built in the classical style, with terraces arranged in three semicircular rows, cut by staircases, on the natural slope of the land. An imposing wall closed the theater behind the stage, supposedly 30m high.