Durocortorum was the name of the city Reims during the Roman era. It was the capital of the Remi tribe and the second largest city in Roman Gaul. Before the Roman conquest of northern Gaul, the city was founded circa 80 BC, served as the capital of the tribe of the Remi. In the course of Julius Caesar's conquest of Gaul (58–51 BC), the Remi allied themselves with the Romans, and, by their fidelity throughout the various Gallic insurrections, secured the special favour of imperial power. At its height in Roman times the city had a population in the range of 30,000 – 50,000 or perhaps up to 100,000, and was an important node in the road system of Gallia Belgica. After the installation of Magnus Maximus in Augusta Treverorum, Durocortorum was renamed Metropolis Civitas Remorum, and no longer served as the capital of Gallia Belgica although it remained the capital of Belgica Secunda. The Latin Durocortōrum comes from the Celtic "Durocorteron" ("round fortress"). It was an oppidum of the tribe of the Remi founded circa 80 BC, and served as its capital. Mentions of Durocortorum from sources during Antiquity in chronological order are: By Ptolemy in his Geography, II, 9, 6 Duricortora (Δουρικορτόρα). By Julius Caesar in his Gallic wars, VI, 44, and to 3. By Strabo in his Geographica, IV, 3, 5. By Ammianus Marcellinus in his Res gestae XV, 11-10. In the proceedings of the Synod of Arles (314) in codex C 37 civitas Remorum, K 27, A 24, D 24 (Item de Galleis. Inbetausius episcopus, Primigenius diaconus de ciuitate Remorum [Reims]). By Saint Jerome, in his letter CXXIII, 15 to Gerchia, Remorum urbs. In the Codex Theodosianus, Valens and Valentinian II are in Durocortorum in 366 and 367 promulgating imperial ordinances (book VIII, 7 given at Durocortorum on 7 April 366 ; book XI, 1 given at Durocortorum 19 May 366 ; ...book XIV, 4 given at Durocortorum 8 June 367).
Emmanuel Pierre Jean Ravalet, Marc Antoine Messer