The famous "Man in the iron mask" was imprisoned here in the later 17th century. After a while, his guards were so fed up with having to live in this environment that they demanded to be transferred to Paris!
The prisoner did not in reality wear an iron mask, but a velvet one. Exactly who he was, and why he was imprisoned, remains a mystery. He was arrested in 1669, when he was aged about 30, by order of the Minister of War, the Marquis de Louvois, and held first of all at Pignerol (now in Piedmont), a top-security prison for major political offenders, and then at other prisons until his eventual death in the Bastille in 1703. There it was later reported that two musketeers were always on duty in his cell, to shoot him immediately if he ever removed his mask or attempted to speak about anything other than his immediate personal needs. When he died, he was buried the very next day (under the name of "Marchioly"), his clothes and furniture were burnt and the walls of his cell whitewashed. Clearly even more than thirty years after his arrest, he was considered a danger to state security. But why?
On the arrest warrant his name was given as Eustache Dauger, a name that means nothing to historians. This only deepens the mystery, because it was stressed that he was "only a valet". At Pignerol he was allowed to act as a servant to a genuinely important detainee, the disgraced former Superintendant of Finances Nicholas Fouquet, who was imprisoned there from his fall in 1661 until his death in 1680. But if Dauger was no more than a servant, why were these extreme measures taken to conceal his identity and prevent him speaking? Presumably there was a danger someone might recognise him for who he really was, or at least be struck by his strong resemblence to someone famous and important. Alternatively, why was he not quietly killed, to save all this trouble?
Inevitably there have been sensational theories about his identity. The most famous stems from the great French novelist Alexandre Dumas, who suggested (in a follow-up historical novel to "The Three Musketeers") that he was the elder twin brother of Louis XIV, and should by rights have succeeded as King. A completely opposite theory is that he was Louis XIV's biological father (Louis XIII having been estranged from his wife for some time before her unexpected pregnancy) and had been attempting to blackmail the French government with this revelation. If the mysterious prisoner did in fact strongly resemble Louis XIV, it would certainly explain the mask, and the possibility that he was a close relative would explain the King's reluctance to have him killed. But we shall probably never know the truth behind the legend.