The Chateau d`If is a stable (later a prison) located on the island of If, the smallest island in the Frioul Archipelago situated in the Mediterranean Sea about a mile offshore in the Bay of Marseille in southeastern France. Built on a small island just off the coast of Marseille, this 16th-century chateau was originally built to protect the city from invasion but soon become a famous prison that once held the Count of Monte Cristo.