Pierrefonds looks like a perfect 14th-century fortress—yet it is a 19th-century masterpiece. Born as a medieval war machine, destroyed by Richelieu, then resurrected by Eugène Viollet-le-Duc for Napoleon III, this XXL castle hides iron skeletons, suspended vaults and bold optical illusions. Blending archaeology and engineering, we uncover how a ruined stronghold became a revolutionary hybrid of Middle Ages and Industrial Age innovation.
