Napoleon, blocked here for two weeks in 1800 by four hundred Austrians, called it a "vilain castel" and had it razed: the Savoys rebuilt it mightier still, and it is this 1830s fortress — never again used in war — that today bars the valley with its three stacked works. Panoramic lifts climb bastion by bastion to the Museum of the Alps.
Cinema has discovered it: the Avengers set Hydra's fortress here.
Our tip: the medieval village of Bard at the fort's feet is a jewel of fifteenth-century houses many skip: walk up through it, and take the lifts down. The temporary exhibitions are often first-rate: check the programme.