What is a flying buttress?

Flying buttresses are essentially external buttressing arches that transfer the lateral thrusts of the roof and vault to piers on the outside of the building that are massive enough to withstand these forces. By transferring lateral thrusts away from the walls, flying buttresses made it possible for masons to increase the size of window openings and reduce the size of interior piers. The flying buttresses along the nave at Chartres Cathedral date to a rebuilding campaign following a destructive fire on June 10, 1194. Modern art and architectural historians often consider the flying buttresses at Chartres to be first fully aestheticized examples because they integrate radial arcades that connect the lower two levels of the flyer arches.  At Chartres, the radial arcade constitutes one of the cathedral’s major exterior motifs and it also appears in the tracery of the rose windows. The new cathedral was consecrated in October 1260.