According to "DK Eyewitness Travel Top 10 Paris":
Originally home to the caretaker and guards of the Palace de Justice, the Conciergerie was turned into a jail at the end of the 14th century. It took its place in history during the French Revolution, when more than 4,000 citizens (including Marie-Antoinette) were held prisoner here, half of whom were guillotined. It remained a prison until 1914.
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