The capital of Roman Helvetia, Aventicum, now Avenches, is Switzerland’s major Roman site and also boasts an extremely interesting medieval quarter. Everything here has been beautifully preserved within a lively, modern, friendly atmosphere. This small town stands on the site of the old Celtic capital of the Helvetii, later the Roman Aventieum, which was sacked by the Alemanni in the middle of the third century A.D. The modern city of Avenches, which is mush small than the ancient one, is perched on the hill that served the Romans as their capitol. The excavated ruins, which are east of the modern town, include an Amphitheater that could seat more than 10,000 spectators, as well as walls and towers that were part of Aventieum's vast fortifications. A Roman Museum is installed in a large square tower whose lower portion dates from the Roman era. Avenches also boats a Renaissance style castle and an 18th century Town Hall, which incorporates a 15th century tower.

A suggested itinerary takes you through the area of the vast amphitheatre (today's venue for a wide variety of events) to the Cigognier column, to the east gate and to the Tornallaz tower. The Roman Museum houses a precious collection of Gallo-Roman artifacts including the famous bust of Emperor Marcus Aurelius as well as remarkably preserved statuettes and mosaics.