What Leonardo da Vinci design was a huge crossbow mounted on a wheeled platform?

Leonardo da Vinci’s giant crossbow was a huge crossbow mounted on a wheeled platform.

Leonardo sketched the weapon around 1488–1490 while working in Milan. Its bow was intended to be exceptionally wide, and a winch mechanism would draw back the powerful string. The wheels and broad base were meant to improve stability and mobility.

The design was probably never built as a practical battlefield weapon. Leonardo’s military drawings often emphasized impressive scale, mechanical ingenuity, and psychological impact as much as realistic engineering. The giant crossbow is therefore best understood as a concept rather than a confirmed working machine.

It is sometimes confused with Leonardo’s multi-barreled cannon and other siege devices. Those designs used firearms or repeated shots, while the giant crossbow relied on one large bow and one projectile.