What large siege weapon did Leonardo da Vinci sketch with a bow about 24 metres wide?

Leonardo da Vinci sketched a giant crossbow with a bow about 24 metres wide.

The weapon was intended to launch large stones or other heavy projectiles, and its exceptional size was meant to create a powerful psychological and physical effect. Leonardo’s drawings show a broad bow mounted on a supporting frame, with a winch or mechanical system for drawing the string. A mechanism was necessary because a person could not pull such a bow by hand.

Leonardo developed the design in the late fifteenth century, when rulers sought imposing artillery and siege machines. The crossbow was a conceptual weapon rather than a documented, successfully deployed battlefield device. Its scale also created major structural and practical problems, including tension, transport, and reliable release.

It is sometimes mistaken for a catapult because both belong to the family of siege weapons. The distinction is mechanical: a crossbow stores energy in a bent bow and releases it through a string, while a catapult usually uses a swinging arm or torsion system.