A few kilometres outside Vallorbe is the underground FortPré-Giroud , built in 1937 to ward off a possible attack from France. The seemingly unremarkable mountain chalet commands views across the Orbe Valley into France and below ground could accommodate 130 men. In its dormitories, canteens, kitchen, telephone exchange and infirmary now stand around 40 military mannequins. Bring warm clothing, as the underground temperature is 8°C. The fort is a 40-minute walk from Vallorbe (follow the Fort 39-45 signs) or a nice drive through forests on a minor back road leading over the mountain ridge to Vaulion.
