Attention, you are about to enter one of the most fascinating corners of the Swiss Réduit heritage: the Promenthouse fortification line. Made up of some 3000 concrete blocks, it was built during the Second World War to prevent the invasion of German tanks from France. It stretches from the village of Bassins in the Jura foothills to Lake Geneva. Reminiscent of a Toblerone chocolate bar (hence the nickname), the tank barriers follow the natural barrier of the Promenthouse-Sérine valley along three rivers, reaching Nyon after a good 18 kilometres. Originally, the dragon’s teeth protruded 50 metres into Lake Geneva to prevent an amphibious attack.
A walk along the Toblerone Trail is a fascinating expedition into the eerie world of wartime Switzerland. But fear not: today the trail has been completely reconquered by peace-loving forest nature. Now almost completely overgrown with moss, ivy and brambles, the toblerones blend naturally into the gently rolling hills. Nevertheless, the somewhat surreal relics from the Réduit are a vivid reminder of an ominous chapter in recent Swiss history.