The Flying Buttress
Architectural Period: Gothic, with precursors in Byzantine and some Romanesque buildings
Famous Examples: Bath Abbey, Notre Dame Cathedral, Amiens Cathedral, Le Mans Cathedral
When I was a kid, I thought that the flying buttress was a wrestling move. I would yell it when I was jumping off my friend Brian's couch onto him. It wasn't until I was studying architectural styles in 7th grade or so that I found out how wrong I was.
I've lately been reading Les Miserables, and my mental life has been full of ancient architecture and historic landmarks. They're not really referred to in Les Mis, but the flavor is still there. It's Paris, after all. Paris, to me, is Notre Dame. And if it weren't for the flying buttress, the world's most famous cathedral would have a much different form.
In the world of architecture, there are quite a few beautiful structural elements that seem to have no purpose other than "looking really cool." But upon closer inquiry, many of them actually did originate out of necessity. Take the flying buttress, for example. Aside from its snicker-worthiness (heh ... you said "buttress" ... heh heh), its name actually makes sense. According to the Encyclopedia Brittanica, a buttress is "an architectural structure built against or projecting from a wall which serves to support or reinforce the wall." It would stand to reason, then, than a flying buttress is the kind that looks more airy or light.
In order to fit the definition of a flying buttress, the structural element in question needs to have two parts: the massive vertical block (the buttress) and an arch (the "flyer") connecting the buttress to the wall. Its purpose? Let's put it this way: if you have a heavy roof, such as a vaulted stone roof, you've got to prop up the walls somehow if you don't want them to crumble outward.
A secondary benefit (but no less important when it comes to cathedrals) is that the support provided by the flyers leaves a lot more space for windows. The stained glass of a cathedral was one of, if not the, most important elements of its design. Stories from the Bible and church history were told in those windows, and that was important because many people at that time couldn't read. Well, with the use of flying buttresses, the pictures got bigger and brighter.
With the advent of smaller church buildings and lighter roofing materials, flying buttresses were no longer needed. And as the Renaissance period brought ancient Greek and Roman forms into vogue, the beautiful structural arches were no longer appreciated. But if I ever build a house, I'm putting flying buttresses on one side of it just for kicks.