The Vaudoise town of Vallorbe lies in a valley basin of the river Orbe, directly on the French border. An inconspicuous chalet is nestled against the slope above Vallorbe. It is the disguised entrance to the fortress "Pré-Giroud".

Up to 200 men who were stationed in the fortress of Vallorbe defended the Jougne Pass and the French border - with field howitzers, cannons and machine guns. Water and food supplies lasted for two months. Filtered air and the fortress's own operating theater guaranteed autonomy as far as the outside world was concerned. "Pré-Giroud", built between 1937 and 1941 and also used during the Second World War, is today part of military cultural history. It is owned by a foundation.

The defence bunkers with their subterranean tunnels, munitions dumps, rooms for the wounded and the sick, and living quarters can be viewed during the summer months. Documentaries and exhibitions offer insight into life in the fortress.