During a visit to Marseille in 1516, King François I assessed the strategic importance of the site and ordered the construction of a fortress. The fortress soon changed roles and became a prison.
Masses of Protestants were thrown into the dungeons from the 17th century. However, the fortress provided rather decent living conditions to wealthy prisoners. The most famous prisoner is undoubtedly José Custodio Faria who Alexandre Dumas immortalised in the Count of Monte-Cristo.

You can still see the hole which Edmond Dantès carved out of the wall in one of the cells. After housing insurgents in 1848 and Communards in 1871, the fortress lost its prison status and opened to the public in 1890.
You can now visit the Château d’If on the regular ferry route.