The capital of Roman Helvetica, Avenches has a wonderfully preserved Roman amphitheater.
Link to Ancient Rome
Originally named Aventicum, this city was a major Roman settlement in the early 2nd century AD. Today, the only remaining Roman structures include the baths of the forum, one of the 73 historic towers, and the theater. The brick and wooden amphitheater ceased to be in use by the 4th century AD.
The Amphitheater Site
There is a fantastic, small museum located in the only remaining tower at the edge of the amphitheater. The museum has a few artifacts as well as a good overview of the history of the site. Definitely worth a stop.
The most fun, though, is that you can walk and run around the amphitheater, pretend you are an ancient Roman and oversee your own gladiator battles. The ancient amphitheater is still in use today. Seating about 16,000, it is the site of summer music festivals.
Avenenches is a small (very charming!) town located in southwestern Switzerland between Lausanne and Bern. It is located on Lake Merton and near (the much larger) Lake Neuchatel.
Learn more about the Avenches Roman Amphitheater here.