During the First World War several rocky areas were adopted and used for military purpose. In 1915 the Austrian army reached the Dolomites, as the neutral Italy declared war to the Austrian-Hungarian Empire. The military high command feared that bypassing the Alps the Italian army could reach the capital city of Vienna in just one week, so it was decided to secure the most important routes and mountain passes in the region. One of these strategic locations was the 2.105 m high Falzarego Pass, connecting the Valle del Boite with various other valleys of the Dolomites. This pass is overlooked by the nearly vertical cliffs of the small Lagazuoi, a 2.700 m high mountain. There was no experience with war in such an extreme and alpine environment and it was almost impossible to attack the enemy when he took shelter above the steep cliffs of the Dolomites. This defensive system, as many others constructed during the Great War, required the construction of cave emplacements, shelters, observation posts and access roads of considerable strategic and architectural importance. Let us try to describe its context as well as its assignment and role which they played during the war and a mark left by them in landscape and memory.