The Château d'If is a fortress (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. It is famous for being one of the settings of Alexandre Dumas' adventure novel The Count of Monte Cristo.
The château is a square, three-story building 28 m long on each side, flanked by three towers with large gun embrasures. The remainder of the island, which only measures 30,000 square meters, is heavily fortified; high ramparts with gun platforms surmount the island's cliffs.
The castle's principal military value was as a deterrent; it never had to fight off an actual attack. The closest that it came to a genuine test of strength was in July 1531, when the Holy Roman Emperor Charles V made preparations to attack Marseille. However, he abandoned the invasion plan, perhaps deterred by the presence of the castle.
This was perhaps fortunate, given the weaknesses identified by the military engineer Vauban in a scathing report in 1701: "The fortifications look like the rock, they are fully rendered, but very roughly and carelessly, with many imperfections. The whole having been very badly built and with little care... All the buildings, very crudely done, are ill made."
The island became internationally famous in the 19th century when Alexandre Dumas used it as a setting for The Count of Monte Cristo, published to widespread acclaim in 1844. In the book, the "Count" (actually the commoner Edmond Dantès) and his mentor, Abbé Faria, were both imprisoned on If. After fourteen years, Dantès makes a daring escape from the castle, becoming the first person ever to do so and survive (in reality, none are known to have done so). He adopts the identity of the Count of Monte Cristo and takes revenge on those who had falsely sent him to the island, driving them into bankruptcy and suicide.
As was common practice in those days, prisoners were treated differently according to their class and wealth. The poorest were literally at the bottom of the pile, being confined to a windowless dungeon under the castle. The wealthiest were much better off, living comparatively comfortably in their own private cells (or pistoles) higher up, with windows, a garderobe and a fireplace. However, they were expected to pay for this privilege, effectively forcing them to fund their own incarceration.
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 Chateau 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 was housed the "Iron Mask." This was prior to the Chateau's opening to the public, and his account cannot be confirmed.
The Château d'If is listed as a monument historique by the French Ministry of Culture.
Contrary to common belief, The Man in the Iron Mask and Marquis de Sade were not prisoners at the Château.