Flying Buttresses. They look lovely, but actually play a large role in keeping the structure steady.
Flying buttress typical of Gothic architecture | Washington National Cathedral...
DIAGRAM: illustrating "flying buttresses". The flying buttresses on Chartres are rather modest compared to later cathedrals.
Clerestory, flying buttress, Chartres Cathedral- Chartres, Eure-et-Loire, France
Beautiful flying buttresses at Notre Dame in Paris
How Gothic architecture was structured. Important: The location and use of flying buttresses and ribbed vaulting.
chapter 9 flying buttress: were diagonal arches that provided support to the structure. It became a major design feature on French cathedrals.
Flying butresses at St. Vitus Cathedral in Prague