Leonardo da Vinci designed a giant crossbow with a bow spanning about 24 meters.
The weapon appears in drawings made during Leonardo’s work for Ludovico Sforza in Milan. It was intended to intimidate enemies and launch a large projectile, combining the familiar principle of a crossbow with an enormous frame. Leonardo proposed wheels and mechanical systems to help move and operate the machine.
The design used a broad bow made from multiple sections and a large stock. Because the bow was so large, the machine required a separate mechanism to draw the string rather than relying on human strength. Its scale made it an impressive piece of military engineering, but there is no firm evidence that it was built and successfully used.
The giant crossbow is sometimes confused with Leonardo’s other siege designs, including fortified vehicles and enormous catapults. Unlike a trebuchet, it stored energy by bending a bow rather than by raising a counterweight.