What weapon did Leonardo da Vinci sketch as a giant crossbow mounted on a wheeled frame?

Leonardo da Vinci sketched a giant crossbow mounted on a wheeled frame as a powerful weapon.

The design appears in Leonardo’s engineering studies, where he explored ways to enlarge and mechanically operate familiar weapons. Its broad bow was supported by a substantial frame, while a winding mechanism would have helped draw the exceptionally heavy string.

The crossbow was intended to launch a large projectile, but there is no reliable evidence that Leonardo’s giant version was built or used in battle. It belongs to his extensive collection of military concepts, many of which remained drawings rather than finished machines.

This invention is often confused with Leonardo’s giant catapult and his multi-barreled organ gun. Those were separate designs with different launching or firing systems.