Ouvrage Castillon was built by a contractor named Borie from November 1931 to October 1934 at a cost of 15.6 million francs.

The avant-poste Baisse-de-Scuvion 43°51′01.9″N 07°28′24.18″E / 43.850528°N 7.4733833°E / 43.850528; 7.4733833 at an altitude of 1,018 metres (3,340 ft)[10] controlled Mont-Mulcier and the Col de Cuore, with 32 men assigned.

The avant-poste Pierre-Pontue 43°50′34.33″N 07°28′52.82″E / 43.8428694°N 7.4813389°E / 43.8428694; 7.4813389 to the south at an altitude of 1,122 metres (3,681 ft)[11] was larger, although it too was assigned 32 men.

[13] Italian troops attacked the avants-postes at Pierre-Pontue and Scuvion, but were discouraged by fire from Castillon itself on the 22nd.

[15] Castillon's war damage was repaired in the 1950s as part of a program to restore many of the gros ouvrages to military usefulness against an advance through Italy by the Warsaw Pact.