Leonardo da Vinci designed a giant crossbow, a six-wheeled siege weapon intended to launch a large bolt.
The design is associated with Leonardo’s military engineering work for Ludovico Sforza, the duke of Milan. Its oversized bow was mounted on a broad wheeled frame, and a winch mechanism was intended to draw the bowstring back. The wheels were arranged to help stabilize and move the weapon.
The giant crossbow was probably a design proposal rather than a battlefield weapon that Leonardo built and used. Its scale made it visually impressive, but a practical siege weapon would also have required strong materials, reliable tensioning, and a way to withstand repeated firing. Leonardo’s military notebooks contain many such ideas, including fortifications, bridges, and artillery concepts.
It is sometimes confused with Leonardo’s armored vehicle, but the two designs had different purposes. The crossbow was an oversized projectile weapon; the armored vehicle was intended as a protected mobile platform.