Vallo Alpino is a defensive mountain line made from 1931 to 1940 by the Italian army in the border towns. In Haute-Roya, the overall design turned towards France, spreads out in an arc on the towns of Tende and La Brigue.
These fortifications use natural or dug caves, or were built of reinforced concrete. They usually have one or two entrances on the front’s back. All the structures on the surface are camouflaged: stones embedded in the concrete, imitation of the forms of rocks, etc.
Vallo Alpino system was divided into 10 sectors (numbered from 1 to 10) divided into sub-sectors, themselves divided into groups of caposaldi (fortifications). Each includes several fortified structures. It consisted of permanent underground or open-air artillery batteries, semi-permanent batteries for medium and large artillery, mixed artillery and infantry, and underground infantry works for the troops. There are also some barracks, some of which were built at the end of the 19th century at Tende’s col, and many of which were built on standard plans around 1936.
The galleries and underground chambers have their vaulted concrete walls generally raised and painted white. The block casemates are covered with a dome or a flat ceiling in slabs on metal girders.
At Tende and La Brigue, the works are spread over two main lines, representing fifteen groups of caposaldi in six sectors.
The first line, to the south, started in 1931, adopts a winding route between the south of La Brigue and west of Tende.
The second line, much less dense, was implemented from 1937. It follows an East-West line between Mount Bertrand and the Sabion massif. It does not include any underground battery, but mixed infantry / artillery.
Dam structures on the ridge between Tende and Limone were built under the front of Fort Central.