What Leonardo da Vinci weapon was designed with a bow about 25 meters wide?

Leonardo da Vinci designed a giant crossbow with a bow about 25 meters wide.

Leonardo drew the weapon around 1488–1490 while working in Milan. Its enormous bow was intended to launch large bolts or stones, and the design included a broad, wheeled base for stability. A winch mechanism would have drawn back the powerful bowstring.

The machine was probably more a demonstration of engineering and military imagination than a practical battlefield weapon. Its huge dimensions created serious problems involving strength, transport, loading time, and accuracy. Leonardo’s drawing emphasizes the mechanism and proportions, but it does not prove that a full-sized working version was built.

The design is sometimes confused with a catapult or a ballista. A crossbow stores energy in a bent bow and releases it through a string, whereas a catapult uses a different throwing mechanism. Leonardo also designed many other military machines, including armored vehicles and bridges.