When modern Paris has overwhelmed you with its boutiques, bicycles, and baguettes, step back in time at two of its most interesting and historic landmarks in the medieval Palais de la Cité, once the residence of the Kings of France. Sainte-Chapelle, with its mesmerizing stained glass windows, once housed Christ's Crown of Thorns, while the Conciergerie became the prison of Marie-Antoinette. Discover two stunning monuments from France's past: a 13th-century chapel with brilliant stained glass and a medieval royal palace that was once home to French royalty. All visitors need to pass through security checks.