Vindonissa

The only Roman legionary fortress of the 1st century AD in Switzerland, located at modern Windisch at the confluence of the Aare and Reuss rivers [1] [2] [3]. Established as a military post around 15 BC during Augustus's Alpine campaign, it grew into a full legionary camp by 15 AD, covering 20 hectares with a 1.8-km encircling wall [1] [2] [3]. The site hosted Switzerland's largest Roman amphitheatre [2] [4]. A Roman underground water canal still functions today, supplying the later Konigsfelden Monastery [2] [5]. The last garrison, Legio XI Claudia, departed in 101 AD when Trajan redeployed it to the Danube region [1] [2]. Listed as a Swiss heritage site of national significance [2].