The Fort stands out in the middle of the steep slopes of the Bard Gorge on an impervious rocky hill and consists of four main bodies (called Opere, to use the terminology of military architecture), placed at different levels between 400 and 467 metres above sea level. The fortress was most likely used for defensive purposes since antiquity. The first evidence of a fortified structure dates back to the 11th century, but the actual fortress only saw the light of day in the 12th century. From 1242, when the lords of Bard were driven out, it passed to the Counts of Savoy. In 1800, the Fort of Bard acted as an obstacle to the onslaught of Napoleon Bonaparte and his 40,000 men who had come down from the Great St. Bernard Pass to sweep across the Po Valley. Napoleon, on his way back to France from Marengo, had the fortress razed to the ground. It was rebuilt between 1830 and 1838 by the military engineer Francesco Antonio Olivero. The Carlo Alberto Opera is the tallest and most impressive of the structures and houses the Museum of the Alps, a multimedia and scientific exhibition illustrating the Alpine territory, with its morphological, naturalistic, geological and climatic characteristics and the changes it has undergone over time. Also in the Carlo Alberto Opera, you can visit the prisons, 24 narrow isolation cells, home to a multimedia exhibition that deals with the famous prisoners who passed through the fort, including Camillo Benso, Count of Cavour. In the Opera di Gola concerts and events take place, the Opera Vittorio, located at the middle level of the fortress, hosts Le Alpi dei ragazzi, a favourite spot for youngsters, who can discover the mountains of the Aosta Valley here while having fun. Opera Ferdinando, at the foot of the fort, houses the Museo delle Frontiere, which tells the story of the western Alps and the relationships between the peoples who inhabited them, and the Fort and Fortifications Museum, dedicated to the evolution of defence works over the centuries, especially in mountain areas.