More than 200 feet long, with massive walls 65 feet high, Fort Boyard sits like a stone warship off the west coast of France.
Construction began in 1801 under Napoleon, ruler of France, who thought the fort would guard against British attack. By the time it was finished, in the 1850s, it was no longer needed for protection.
For a brief time the fort was used as a prison, but mostly it sat abandoned.
In the 1980s it was restored as the set for the French TV show "Fort Boyard." Contestants compete in physical challenges for money.
In the summer, the fort has a fireworks display.