Together with the Roman theatre, the Arch of Augustus is the symbol of the city of Aosta.
The monument was erected in honour of the emperor himself after his victory over the native population, the Salassi, in 25 BC, the same year in which Augusta Prætoria was founded.

Architecturally, it is an honorary round arch. Originally there was an attic at the top of it that housed a quadriga, now lost.
The arch, as is traditional for such monuments, was placed at the entrance to the Roman city to impress anyone arriving there from the road to Gaul.

In the Middle Ages, the arch was named Saint-Vout because of an image of the Saviour present there, replaced today by the Crucifix that can be seen on arrival in the city and that was placed there to protect the city from the flooding of the Buthier torrent that flows a stone’s throw from the monument.