The first reference to Grenoble dates back to July 43 BC. At that time, the small town was called Cularo and had been founded by the Gallic people known as the Allobroges. In 292 the western emperor Maximian built walls around the town after elevating it to the rank of “city”. These Gallo-Roman walls protected the urban area and served as a status of Civitas. The vestiges of the Gallo-Roman wall are now a landmark of this era.
In 381, wishing to thank and honor the emperor Gratian for having created there a bishopric, the inhabitants of Cularo renamed their town Gratianopolis. Its name would subsequently metamorphose into Grenoble.
Dating back from the Gallo-Roman period (4th century), Saint-Laurent crypt and the Grenoble baptistery have been preserved to this day; the latter had been used until the 9th century and then rediscovered in 1989 during the construction of the tramway tracks and excavated until 1996. Several sections of the Gallo-Roman city wall can also be seen in the old town, especially in rue Lafayette.
- Ad Familiares, 10, 23 Letter 876
- William Smith, ed. (1872) . "Cularo". Dictionary of Greek and Roman Geography. London: John Murray.