The first mention of a fortified structure in the place dates from the 7th century, when a chronicler of the Abbey of Novalesa wrote of a fortification on the spur overlooking Exilles, perhaps destroyed by the Franks.
Between 1494 and 1496 it was used as an ammunition depot by Charles VIII of France, who enlarged the main entrance and enrolled peasants of the area to defend it.
In 1591 it was recaptured by the French after a short siege, but two years later Charles Emmanuel I of Savoy took it back and strengthened it, in particular on the side facing the upper Susa Valley.
The fort was opened to the public in 2000, housing the Museo Nazionale della Montagna (National Mountain Museum) and occasional exhibitions.
The famous historical character known as L'homme au masque de fer (The Man in the Iron Mask) spent some years captive in the fortress jail.