Forever known as the prison setting for Alexandre Dumas' "The Count of Monte Cristo", this 16th century fortress-turned-penitentiary situated on the small Mediterranean island of If is worth investigating as much for its history and architecture as it is for its fictional intrigue. The structure was last used as a prison during WWI, however its Alcatraz-esque reputation for thwarting would-be fugitives dates back to 1580. These days, the interior of the edifice is pretty standard, containing a series of worn empty cells and a small museum, but the scenic beauty of the sea combined with the presence of so much literary and historic significance makes for a pretty evocative experience. The ferry to the island takes around 20 minutes, and entrance to the Chateau will set you back around 6 euro ($8).
Location:If Island, Frioul Archipelago, 1 mile (1.6 km) off the coast of Marseille, France
Note:As an added bonus, the ferry returning from Chateau d'If stops at other islands in the Frioul archipelago. In particular, Ile de Ratonneau and Ile de Pomegues, connected by a pedestrian land bridge and are skirted by miles of walking trails, are a safe bet for some scenic beach-side leg stretching.