What unusually large weapon did Leonardo da Vinci design with a 25-metre bow?

Leonardo da Vinci designed a giant crossbow with a bow approximately 25 metres wide.

The weapon appears in Leonardo’s military drawings from the late 15th century. Its enormous bow was mounted on a wheeled frame, and Leonardo included a mechanism intended to draw the bowstring back. The large scale was meant to create a powerful psychological and military effect as well as to launch a heavy projectile.

Unlike a handheld crossbow, this design would have required substantial support equipment and a carefully engineered loading system. There is no reliable evidence that Leonardo’s giant crossbow was built or used in battle. Modern reconstructions therefore test the drawings rather than restore a surviving weapon.

The design is sometimes confused with a catapult or ballista because all are ancient or early artillery concepts. A crossbow stores energy by bending a bow, while catapults use other tension, torsion, or leverage arrangements.