In the city Saint-Romain-en-Gal at the other site of the river is the Vienne Musee et sites archeologiques. Filled with mosaics and other objects found in Vienne and the archeologic site at the museum.

The oppidum of the Allobroges became a Roman colony about 47 BCE under Julius Caesar, but the Allobroges managed to expel them; the exiles then founded the colony of Lugdunum (today’s Lyon).Herod Archelaus was exiled here in 6 CE. During the early Empire, Vienna (as the Romans called it—not to be confused with today’s Vienna) regained all its former privileges as a Roman colony. Later it became a provincial capital of the Dioecesis Viennensis. In 257 Postumus was proclaimed emperor here of a short-lived Gallo-Roman empire. The town served as his short-lived provincial empire for a few years.

On the bank of the Gère are traces of the ramparts of the old Roman city, and on Mont Pipet (east of the town) are the remains of a Roman theatre, while the ruined thirteenth-century castle there was built on Roman footings. Several ancient aqueducts and traces of Roman roads can still be seen.

There are several  important Roman monuments still standing at Vienne.
One is the Early Imperial temple of Augustus and Livia, a rectangular peripteral building of the Corinthian order, erected by the emperor Claudius, which owes its survival, like the Maison Carrée at Nîmes, to being converted to a church soon after the Theodosian decrees and later rededicated as “Notre Dame de Vie.” (During the Revolutionary Reign of Terror it was used for the local Festival of Reason.)
The Roman monument is the Plan de l’Aiguille, a truncated pyramid resting on a portico with four arches, from the Roman circus.
Archaeological Gardens of Cybele, an open garden home to Gallo-Roman remains in a timeless setting: a portico which may have once been a part of the thermal baths or the wall enclosing the theatre.

La Pyramide

Roman Theatre

Temple of Augustus and Livia

Archaeological Gardens of Cybele