What siege weapon did Leonardo da Vinci design with a bow spanning roughly 25 metres?

Leonardo da Vinci designed a giant crossbow with a bow spanning roughly 25 metres.

The weapon appears in Leonardo’s studies of military engineering from the late fifteenth century. Its enormous bow was intended to launch large projectiles, and the design included a mechanism for drawing the bowstring rather than relying on human strength alone.

Leonardo’s giant crossbow is generally understood as a design study rather than a weapon known to have entered service. Its exaggerated scale reflects Renaissance interest in powerful siege equipment and in using mechanical advantage to amplify force.

It is sometimes confused with Leonardo’s other military sketches, including his multi-barrel gun and armoured vehicle. Unlike those devices, the crossbow is a single-projectile weapon based on the ancient bow-and-string principle.