The Cellon-Schulter tunnel is the most spectacular part of this route. It was dug by Austro-Hungarian soldiers in 1916 to connect the valley bottom with the military posts located on the Schulter viewpoint. It allowed soldiers to climb this side of the mountain while sheltered from Italian fire coming from the posts on Mt. Pal Piccolo.
The tunnel is 183 metres long and has a difference in altitude of 110 metres. The first section is almost entirely dark, while the second is flanked by several openings to the north, from which the sunlight filters in. Although it is quite steep and the rocks are slippery, it can be walked through quite easily thanks to the restoration work carried out by the Alpine guides of the Austrian Army in1987. The steel cable runs all along the walls and iron brackets are placed in the most critical points.
Obviously this tunnel should be undertaken with a ferrata kit, a powerful torch (front torch recommended) and a helmet.
