Leonardo da Vinci’s enormous siege weapon with a nearly 25-metre bow was a giant crossbow.
Leonardo designed the weapon for military use in the late fifteenth century. His drawing shows a bow about 24 metres wide mounted on a wheeled base. A large winch would draw back the bowstring, allowing the machine to launch a large projectile. The broad bow was intended to improve psychological impact as well as destructive power.
The machine was not a giant handheld crossbow. Its scale required a supporting frame, wheels, and mechanical winding equipment, making it a siege engine. Leonardo’s design also included details for moving and aiming the weapon, reflecting his interest in practical military engineering.
No evidence shows that Leonardo’s specific crossbow entered service. Reconstructions can test the idea, but their results depend on modern interpretations of the missing construction details and materials.