Monte Viso Tunnel
The Monte Viso Tunnel (Italian: Buco di Viso) is an Alpine tunnel built during the Renaissance and located eight kilometres north of Monviso (Cottian Alps), northern Italy. It is 75 m long, 3 m wide, and located at 2,882 metres linking the modern Italian province of Cuneo and the French department of Hautes-Alpes.
The tunnel was built between 1478 and 1480  by order of Ludovico II, marquis of Saluzzo, in collaboration with Louis XI of France, to connect the Dauphiné and Provence to his domains. It was used mostly for trade - salt and cloth from France, rice, wool and animal skins from Italy - and the neighbouring communities in the Guil valley (France) and Po valley (Italy) benefited considerably.
But the tunnel also saw military use. In 1486 Ludovico II escaped through the tunnel to France when he fled Saluzzo; and according to certain historians, the French king Francois I led his artillery through the tunnel in 1525 in order to attack the emperor Charles V. It is likely that other French kings including Charles VIII and Louis XII also passed through the tunnel on their way to Italy.
However, while neighbouring communities continued to value the tunnel for the increased trade that it enabled, it was frequently closed during the following centuries through landslides and rockfalls. Moreover, after Charles Emmanuel of Savoy conquered the Marquisate of Saluzzo, he decided to close the tunnel permanently.
In 1998 the tunnel was cleared and reopened under the auspices of the Rotary Club of Saluzzo, who have erected information panels at both entrances (from which the above historical information is taken). Access to the tunnel is still occasionally obstructed by rockfalls, but the route is now an established link within the network of mountain paths in the Monte Viso-Queyras-upper Po valley district, as an alternative to crossing the summit of the Col de la Traversette (2947m).
The tunnel is about 75 metres long and unlit: take a torch (flashlight). Headroom in certain sections is only 1m70 (5 ft 7 in) and at one point only 1m40 (4 ft 7 in) - walkers carrying a large rucksack may find it a bit of a squeeze. Entering the tunnel at the French end necessitates climbing down some fallen rock to reach the floor of the tunnel. Additionally, the French entrance is normally blocked by snow until well into the summer season.
- information panel at Italian entrance to the tunnel
- Kev Reynolds, "Walking in the Alps", Cicerone, 2nd edition 2005
- information panel at Italian entrance of the tunnel