Following the Sixth Battle of the Isonzo, the Italian Military Command had to build new defensive lines to prevent new attacks by the Austrian Army, in the event that the latter came into proximity with the Comeno Karst (now part of Slovenia). Following an order by the Duke of AostaEmanuele Filiberto of Savoy, Commander of the Third Army, the whole section west of the Valley was therefore fortified and entrenched.
To visit this line, you do not need to follow a specific route: after the wooden bridge connecting the trail to the trenches, you can turn left and walk straight or descend into the sinkhole on the right, where some Italian barracks were probably erected for the Italian troops in 1917.
From here, on the left, you can access an underground tunnel that allowed soldiers to move from the trench to the sinkhole while protecting from possible enemy bombing. Halfway, on the right, a second tunnel opens up, narrow and darker (you need a torch here), while at the end of the main tunnel a spectacular spiral staircase in concrete leads back to the entrenched line; it is about 100m long, featuring a zigzag pattern and several buttresses and slits.
