Aosta in ancient times was the center of the Celtic-Ligurian tribe salassov, interfere with the free penetration of the Romans in Gaul. For the first time the Romans realized the threat posed by the Alpine tribes during the Second Punic War, when the Gauls supported the invasion of Italy, the Carthaginian army of Hannibal (218 BC.) .. Salassy later were attacked by the Romans in 143 BC. e. AT Appiah consul Claudius Pulcher, who had hoped to get an easy win and get the triumph. Defeated, he was forced to turn to the prophecies Sivillovyh books and only won .
With the conquest of Gaul in the I century BC. e. I needed a safe passage through the Great and Little St. Bernard. Therefore, in 25 BC. e. August ordered Terence Varro Muren lead another expedition against salassov as they continued to hinder the passage of the Roman legions into Gaul and the valley of the Upper Rhine. Moray took the city, sold into slavery about 44 thousand. Salassov .
At the site of the camp Varro Murena three thousand veterans founded the city named them in honor of the Emperor “August Pretoria Salassov” (lat. Augusta Praetoria Salassorum) .
In the Aosta Valley the Romans 12 BC. e. built the so-called Gallic road (Publica or strata), which in 47 AD. e. It was paved with stone. In the Middle Ages it became a famous pilgrimage road – Via Francigena .
With the fall of the Western Roman Empire, the city repeatedly passed from hand to hand. At the beginning of the VI century the town was part of the Ostrogothic kingdom. Then, the city claimed by the Franks and the Lombards, in the end of 575 year ceded his Frankish king Guntram.