Fort de Joux is a castle fortress located in the Doubs department in eastern France. The fort has a rich history and was initially built in the 11th century, making it one of the oldest forts in the region. Over the centuries, the fort has been used for a variety of purposes, including as a prison, military barracks, and even as a military hospital.

One of the most famous inmates of the Fort de Joux was the French military leader Toussaint Louverture, who was imprisoned here in 1803. Other notable prisoners included the Marquis de Sade and Heinrich Himmler during World War II.

Today, the Fort de Joux is open to the public as a museum and historical site. Visitors can explore the various sections of the fort, including the prison cells and the guard rooms. The museum also contains a collection of weapons and other military artifacts, as well as exhibits on the history of the fort and its role in French military history. Additionally, the fort offers guided tours and hosts special events throughout the year, such as reenactments and historical festivals.