Outside Cannes

Slightly outside Cannes, there is a famous monastery where the fellow who converted the "heathen Irish" to Catholicism studied. What would he have done if he had known about car bombs, the Brighton hotel and The Troubles? I bet he'd have gone right ahead with his plan regardless. Religious conviction never seems to take a backseat to worldly concerns.

Monastery outside of Cannes

Slightly closer to town, there is the famous prison where the Man in the Iron Mask was kept a prisoner. In reality, he wore a velvet mask. But that doesn't make good movie fodder.

Prison where the Man in the Iron Mask was imprisoned

If you're the bastard child of a king and need to be imprisoned for the rest of your life and forced to wear a mask,
this is not a bad place to do it