What large military crossbow did Leonardo da Vinci design?

Leonardo da Vinci designed a giant crossbow, a large siege weapon intended to launch heavy bolts.

His drawing shows an enormous bow mounted on a wheeled frame. The design included a broad bow, a loading mechanism, and supports intended to manage the weapon’s size. Leonardo’s purpose was to create a weapon that would intimidate enemies as well as deliver a powerful projectile.

The giant crossbow appears in Leonardo’s military notebooks, but there is no reliable evidence that his full-scale design was successfully built or used in battle. It therefore belongs mainly to the history of military engineering and Renaissance design.

It is sometimes confused with a ballista. A ballista is an ancient torsion-powered missile engine, whereas Leonardo’s design is explicitly based on the crossbow’s bent bow and string.