This building had a number of uses during it's time. In the 6th century it was a palace, in the 14th century it became the Parliament of Paris and later that century a prison.
During the revolution the building was taken over and used to house anyone per seemed to be an enemy of the revolution. Long story short, this is where Queen Marie-Antoinette was held for a little over 70 days before she was executed. The only positive was she was wealthy enough to have a private room and like everyone else executed was allowed to enjoy a feast prior to the deed being done.