The Palais de Justice (French pronunciation: ​[palɛ də ʒystis]; '"Palace of Justice"), formerly the Palais de la Cité ("Palace of the City"), is located on the Boulevard du Palais in the Île de la Cité in central Paris, France. Among the oldest surviving buildings of the former royal palace are the Sainte Chapelle (built c. 1240, during the reign of Louis IX) and the Conciergerie, a former prison, now a museum, where Marie Antoinette was imprisoned before being executed on the guillotine. The justice of the state has been dispensed at this site since medieval times.