Leonardo da Vinci’s giant crossbow was a huge bow intended to fire a projectile over a long distance.
The design belongs to Leonardo’s military studies in Milan near the end of the fifteenth century. He enlarged the ordinary crossbow dramatically, giving it a broad bow, a heavy supporting structure, and a mechanism for drawing the string. Leonardo also showed the machine on wheels, suggesting that mobility was part of the design rather than an afterthought.
Its scale made the weapon visually impressive, but scale alone would not guarantee battlefield success. The bow and frame would have faced severe stresses, and the design may have been more useful as a demonstration of engineering ambition than as a practical artillery replacement. No surviving evidence proves that the full-sized machine operated successfully.
The giant crossbow is often mixed up with Leonardo’s other siege concepts, including catapults and a giant crossbow sometimes shown in modern reconstructions. Its defining feature is a tensioned bow, not a swinging throwing arm.