What huge weapon did Leonardo da Vinci sketch with a flexible bow nearly 25 metres wide?

Leonardo da Vinci sketched a giant crossbow, a siege weapon intended to launch very large bolts.

The drawing dates from the late 15th century, when Italian states competed to develop powerful artillery and defensive technology. Leonardo's design used a bow almost 25 metres wide, mounted on a wheeled frame. A winding mechanism would draw the bowstring back before release.

The weapon was probably intended as a psychological and military device as much as a practical battlefield arm. Its enormous size created serious problems involving strength, transport, aiming and safe operation. No evidence shows that Leonardo's particular crossbow was built or successfully fired.

It is often confused with a ballista or a catapult. A crossbow stores energy in a bow and releases it through a string, whereas a catapult generally uses a throwing arm. Leonardo's sketch demonstrates his interest in scaling familiar mechanisms into spectacular siege machines.