What weapon did Leonardo da Vinci design with a very wide frame and multiple bowstrings?

Leonardo da Vinci designed a giant crossbow with a very wide frame and multiple bowstrings.

Leonardo sketched the giant crossbow in the late 15th century while developing military machines for the Milanese court. Its unusually large bow was mounted on a wheeled frame, and a mechanical system was intended to draw the bowstring. The design aimed to launch a large projectile over a considerable distance, although no evidence shows that Leonardo’s exact machine was built or used in battle.

The crossbow reflects Leonardo’s interest in combining mechanical advantage with dramatic visual scale. It is sometimes described as an artillery weapon, but it remained a design concept rather than a field-tested cannon. Reconstructions differ because the surviving drawings leave questions about materials, dimensions, and the exact method of tensioning the bow.