The Île d'If, situated 3.5 km (2+1⁄8 mi) west of the Old Port of Marseille, spans 3 hectares (0.03 km2). The island is extensively fortified, featuring tall ramparts with gun platforms atop the cliffs that tower over the surrounding sea. Other than the fortress, the island remains unpopulated.
The château is a three-story, square building measuring 28 meters (92 feet) on each side, with three towers that have large gun embrasures. King Francis I ordered its construction from 1524-31 after recognizing the island's strategic importance in defending the coastline from sea-based attacks during his visit in 1516.
Although the castle's military value was primarily as a deterrent, it never had to face an actual attack. The closest it came to being tested was in July 1531 when the Holy Roman Emperor Charles V made plans to attack Marseille, but ultimately abandoned them.
In 1701, military engineer Vauban criticized the château's fortifications, claiming that they were poorly built, roughly rendered with many imperfections, and ill-made. He questioned its ability to defend against a real attack.
Following General Jean Baptiste Kléber's assassination in Cairo in 1800, his embalmed body was repatriated to France. First Consul Napoleon Bonaparte, fearing that Kléber's tomb would become a symbol of Republicanism, ordered that the body stay at the château for 18 years. Eventually, King Louis XVIII granted Kléber a proper burial in his hometown of Strasbourg.
The Château d'If was an ideal prison due to its isolated location and treacherous offshore currents, similar to California's Alcatraz in more recent times. It gained notoriety as a dumping ground for political and religious detainees, making it one of France's most feared jails. Over 3,500 Huguenots and Paris Commune leader Gaston Crémieux were among those sent to the prison.
The island's fame reached an international level in the 19th century after Alexandre Dumas used it as a setting for his famous novel, The Count of Monte Cristo, in 1844. The novel's protagonist, Edmond Dantès, along with his mentor, Abbé Faria, were imprisoned in the castle, and Dantès made a daring escape after fourteen years, becoming the first person to do so and survive. While no one in reality is known to have accomplished this, a roughly hewn dungeon in honor of Dantès is maintained as a tourist attraction in the modern-day Château d'If.
As was common practice in those days, prisoners were treated differently based on their class and wealth. The poorest were confined to windowless dungeons at the bottom of the castle, with perhaps twenty or more prisoners to a cell. However, the wealthy inmates were able to pay for their own private cells, known as "pistoles," higher up in the castle, complete with windows, a garderobe, and a fireplace.
At the close of the 19th century, the château was no longer utilized as a prison and was disarmed, allowing it to be accessible to the public as of September 23, 1890. Access to the château is available by boat from Marseille's old port. Its fame is derived from its depiction in Dumas' novel, The Count of Monte Cristo, which has resulted in it becoming a popular tourist attraction.
During a prolonged pleasure excursion in July 1867, Mark Twain paid a visit to the château, where he was guided through the prison's cells, one of which was supposedly home to the "Iron Mask." Although a sign at the château identifies it as the "Prison dite de l'Homme au Masque de Fer" ("Said to be the prison of the Man in the Iron Mask"), this is probably only a legend since the Man in the Iron Mask was never actually held at the Château d'If.
The French Ministry of Culture has listed the Château d'If as a monument historique.
The Château d'If, known for its prominent role in Alexandre Dumas' novel The Count of Monte Cristo, has been represented by various locations in film adaptations.
In the 2002 movie starring Jim Caviezel, Saint Mary's Tower on Comino, the smallest inhabited island of Malta, served as the fortress. This cliff-top watchtower can be viewed from the ferry crossing between Malta and Gozo.
The Chateau d'If also appears in a 1949 short story by Jack Vance, titled the same as the fortress.
The location was featured in the 1971 film The French Connection, where it served as the spot for the finalization of a drug shipment.
In the radio comedy series The Goon Show's episode "Tales of Old Dartmoor" from 1956, Dartmoor Prison is put to sea to visit the Château d'If as part of a treasure hunt.
Finally, in the Clive Cussler novel Spartan Gold published in 2010, the Château d'If is visited by the main characters as part of their search for hidden treasure.