Chateau Gaillard is a ruined medieval castle, located 300 ft above the commune of Les Andelys overlooking the River Seine, in Normandy, France. It is located some 59 miles north-west of Paris and 25 miles from Rouen. Construction began in 1196 under the auspices of Richard the Lionheart, who was simultaneously King of England and feudal Duke of Normandy.