Flying buttresses allowed Gothic cathedrals to replace thick stone walls with massive stained glass windows

Flying buttresses revolutionized medieval architecture by channeling the outward thrust of heavy masonry vaults away from the walls and into external piers. At Notre-Dame de Paris, completed around 1163, this mechanism supported walls reaching 35 meters in height. By using precise geometry and angled struts to transfer lateral loads five meters away from the main structure, architects freed the walls from their traditional load-bearing duties.