From the beginning of the Middle Ages, castles have imposed themselves as symbols of power. Over time, France will cover itself with fortresses built according to almost identical plans. It was in the 12th and 13th centuries that castles took their typical form and truly knew their golden age! Their architecture will freeze for eternity the very image of these medieval buildings. How to explain this prosperous period? What technologies did the architects of the Middle Ages deploy to accomplish such monumental works? To better understand it, we will follow a group of medieval history enthusiasts. Together, they imagined a crazy project: to build a real fortified castle using the methods of the 13th century. Through this titanic challenge, this documentary finally pierces the mysteries of the great builders of History.