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, which was not yet open to the public, and inside the cells, one of which he says housed the "Iron Mask". There is a sign at the château that says "Prison dite de l'Homme au Masque de Fer" ("Said to be the prison of the Man in the Iron Mask"), but this is likely only legend since the famed Man in the Iron Mask was never held at the Château d'If.