Fortificazioni del Colle della Croce, Military fortification in La Thuile, Italy.

Fortificazioni del Colle della Croce is an underground fortress complex with stone walls positioned along the ridge between Mont Cormet and Colle San Carlo. The site features enclosed chambers and defensive positions that remain visible today.

A small storehouse and an eastern redoubt on the Colle della Croce date from between 1691 and 1704, linked to the works of Estienne-Arnod. Modern fortifications in the Aosta Valley began in 1924, and in the late 1930s works of the 7000 type were built in Morgex territory. The underground fortress at the pass was dug in the first years of the Second World War, and construction stopped with the war, leaving Alpine Wall works unfinished; after 1947 many border structures were destroyed or abandoned.

The fortification shows Italian military building practices from the 1930s, using local methods and materials from the Aosta Valley region. You can see how engineers adapted construction techniques to the mountain environment.

Access is on foot from the car park near the La Genzianella bar, along the road to Colle San Carlo, following trail marker 15 for Lago d'Arpy. After about ten minutes you reach the entrance of an underground fortress dug in the early years of the Second World War. Continue to the fork, keep right for Colle della Croce, and climb the rocky ridge on the military road, at times held by dry-stone walls, to the saddle below Punta della Croce.

The site's two fortini, Works 9 and 10, stand beside far older remains: a small storehouse on the pass and an eastern redoubt dated between 1691 and 1704, linked to the works of Estienne-Arnod. In the 2010s Morgex and La Thuile placed two information panels near the ruins under the project "Balades à deux voix: entre histoire et nature".