The extraordinary complex of military archaeology known as the Cadorna Line, which runs along the border between Italy and Switzerland, was a line of fortifications devised by General Luigi Cadorna (originally from Pallanza) to protect the territory in the eventuality of attack from Austria-Germany during the First World War.  Between 1916 and 1918 thousands of men and women worked on the construction of this dense network of military mule-tracks, trenches, artillery positions, lookout posts, redoubts, first aid posts, logistical structures and command centres.

The fortifications had no small impact on the environment, increasing the mountain road system in these areas with over 300 km of roads and almost 400 km of mule-tracks, in addition to the 72 km of trenches which in some sections are still practicable today. The Cadorna Line is thus not just a highly unusual itinerary for a hiking tour on foot or by mountain bike, but also interesting historically.

The strategic importance of these places in controlling the territory has recently been confirmed by the discovery of a Celtic-Roman necropolis; the area was also occupied by the partisan groups of the Ossola Republic in 1944.

The best examples of the fortifications are the tunnels and lookout on Monte Morissolo, the ring of trenches on the top of Monte Spalavera, and the structures on Monte Carza.