Ancient Arelate.

The Roman Theatre at Arles, part of the complex of ruins that date from the First Century BC from the time of the Republic and the Civil War between Julius Caesar and Pompey Magnus, when the town was an important trading port as it had been under the Phoencians, and second only to Marseille in the province.

Ultimately, Arles would be the seat of the Western Roman Empire under Constantin III in 408AD.