a Conciergerie was originally built as a medieval palace and later became infamous during the Reign of Terror as "the antechamber to the guillotine" — a prison where hundreds of people were held before being executed. Marie Antoinette was famously imprisoned in la Conciergerie during the weeks before she was beheaded at the Place de la Concorde. These days you can tour la Conciergerie to get a glimpse into the lives of the prisoners who were held there, and also to enjoy the beautiful gothic architecture of the place, and visit its various non-prison-related temporary exhibits.