Château D'If Fortress On The Island Of If, Frioul Archipelago, Bay Of Marseille, Mediterranean Sea, France

The château today
The château's use as a prison ceased at the end of the 19th century. It was demilitarized and opened to the public on September 23, 1890. It can now be reached by boat from Marseille's old port. Its fame as the setting for Dumas' novel has made it a popular tourist destination.
Mark Twain visited the château in July, 1867 during a months long pleasure excursion. He recounts his visit in his book, The Innocents Abroad. He says a guide took his party into the prison, inside cells, and showed him the cell in which housed the "Iron Mask." This was prior to the château opening to the public. There is a sign at the château that says "Prison dite de l'Homme au Masque de Fer." This is likely only legend since the Man in the Iron Mask was never held at the Chateau d'If.
The Château d'If is listed as a monument historique by the French Ministry of Culture.