After their attempted exodus in 58 B.C., and their defeat at the hands of the troops of Julius Caesar near Bibracte, the four Helvetic tribes returned to the Swiss Plateau.We have no precise information concerning the founding of Aventicum. But after the final takeover by Rome of the territory that today constitutes Switzerland in about 15 B.C., Aventicum became the capital of the «Helvetii», mainly due to its strategic position in the Roman road network. It also had direct access to waterways, thanks to a canal that connected its outskirts with a port on Lake Morat.
Under the rule of Emperor Vespasian, approximately 71 or 72 A.D., the town was given the status of a colony.
Most of the buildings still visible today were built after this date. They are exclusively public buildings - private lodgings, artisans' workshops or engineering constructions such as aqueducts, streets and sewers lie beneath the residential or commercial quarters of modern Avenches and have therefore not been restored.
A part of the town wall with the eastern gate and the «Tornallaz», the only surviving watchtower of the 73 that used to surround the town, the baths near the forum, the theatre, the Cigognier sanctuary, the Grange-des-Dîmes temple, the amphitheater and vestiges of the western gate are all accessible to visitors. Information panels have been provided on each site, and visits are free of charge.
Aventicum reached its full bloom in the second and third centuries A.D. With a population of over 20 000, it was well integrated into the Empire's vast commercial and communications network. Around 275 or 277 A.D. the Alamanni raided the town, destroying large parts of it. Although it continued to exist, it never entirely recovered from this blow. Vestiges from Late Antiquity are still rare. Officially, in our region the Roman period ended in 455 A.D.
Today, numerous emergency digs temporarily uncover subsisting parts of public or private buildings, before they disappear again beneath some modern construction.