Arches: Different types and styles

While searching the internet I found this page on Wikapedia demonstrating differnet arches.

An arch is a curved structure capable of spanning a space while supporting significant weight (e.g. a doorway in a stone wall). The arch appeared in Mesopotamia, Indus Valley civilization, Egypt, Assyria, Etruria, and later refined in Ancient Rome. The arch became an important technique in cathedral building and is still used today in some modern structures such as bridges.

http://en.wikipedia.org/wiki/Arch