What weapon did Leonardo da Vinci sketch with a bow roughly 25 metres wide?

Leonardo da Vinci sketched a giant crossbow with a bow roughly 25 metres wide.

The design appears in Leonardo’s Codex Atlanticus and was intended as a dramatic siege weapon. Its enormous bow was mounted on a wheeled platform, while a mechanical system would draw back the string. The large scale was meant to increase intimidation and projectile range, although the machine was probably more practical as a design study than as a proven battlefield weapon.

Leonardo’s military drawings often emphasized psychological impact as well as engineering. The crossbow’s size made it visually spectacular, but large flexible bows create serious structural and mechanical challenges. No authenticated original giant crossbow survives.

It should not be confused with a ballista or a catapult. A crossbow stores energy by bending a bow and releasing a string; catapults and ballistae use different structural arrangements and launching mechanisms.