The Fort de Joux (French pronunciation: [fɔʁ də ʒu]) or Château de Joux (French pronunciation: [ʃato də ʒu]) is a castle, later transformed into a fort, located in La Cluse-et-Mijoux in the Doubs department in the Jura Mountains of France.

In 1454, Philip the Good, Duke of Burgundy, bought the château and transformed it into a border fort, adding a moat and barracks.

In 1879, Captain (later Marshal) Joseph Joffre, then a military engineering officer, modernised the château and transformed it into a fort included in the Maginot Line to prevent German invasion from Swiss territory.

In that capacity, the château is best known for imprisoning several famous figures, including Mirabeau, Heinrich von Kleist, and the leader of the Haitian Revolution, Toussaint Louverture, who died there on 7 April 1803.

[3] In addition to being used as a prison, the château played a part in the defence of the region until the First World War.