As some people know I am a big fan of catapult related ideas. If you don't have an idea what a catapult is take a look left. This is a replica of an ancient catapult from France.

The basic idea is to propel heavy object (stone) with a lever system and throw it as fast and hard against a target (army or walls). Usually these catapults were used to breach walls of fortresses during wars as it took a good time to set them up.

For further informations please visit the brilliant Wikipedia article.