What's a Barrel Vault?
Roman baths of Cluny in Paris
Once you've built an arch, you know how to make a doorway or a window without having to use big expensive beams. But how do you make the whole roof that way?
Easy: you stick a whole lot of arches together in a row, and that makes a roof. That's a barrel vault: an arch over and over. (This one is in the Roman baths at Cluny in Paris).
They're called barrel vaults because they look like the inside of a barrel.
Parthian Arch of Sapor (Iraq, 200 AD)
The earliest barrel vaults were built by people living in the Roman Empire, who used them a lot for roofing. The Romans built barrel vaults all over Europe and North Africa. People in the Parthian Empire, about the same time, also used barrel vaults.
In the Middle Ages, architects also used barrel vaults to put stone roofs on Romanesque churches and cathedrals. By the late 1100s AD, however, most architects were using a more complicated kind of stone roof called a groin vault.
Arches to Zigzags: An Architecture ABC, by Michael J. Crosbie (2000). Shows what an arch is, or a gable, or an eave. For younger kids.
Eyewitness: Building, by Philip Wilkinson, Dave King, and Geoff Dann (2000). Lavishly illustrated, like other Eyewitness books for kids, and with good explanations of most architectural terms.
Cathedral: The Story of Its Construction, by David Macaulay (1981). Beautiful drawings and clear text explain exactly how medieval craftsmen built a groined vault. For kids.