Château d'If is a fortress turned prison located on the island of If, the smallest island in the Frioul archipelago situated in the Mediterranean Sea about 1.5 kilometers offshore from the city of Marseille in France. Constructed under the orders of King Francis I of France, it was built between 1524 and 1531. The fortress was originally a military outpost to protect Marseille from invasions and later became notorious as a state prison. Its fame skyrocketed after Alexandre Dumas featured it in his literary classic 'The Count of Monte Cristo,' where the main character Edmond Dantès is imprisoned before making a dramatic escape. Château d'If has since been emblematic of political and historical intrigue. The prison cells and the castle structure have been well-preserved, and visitors can explore them to experience a piece of French history. Today, it is a popular tourist destination, providing panoramic views of the Marseille coastline and the surrounding sea.