What oversized weapon did Leonardo da Vinci design with a bow over 20 metres wide?

Leonardo da Vinci designed a giant crossbow with a bow more than 20 metres wide.

The weapon appears in Leonardo's military notebooks from the late 15th century. Its enormous bow was intended to launch large stones or other projectiles and to frighten an enemy through its scale. Leonardo proposed mechanical systems to draw the bowstring, because human strength alone would not have been sufficient.

The design included wheels or a movable platform, allowing the weapon to be transported and aimed. Like many of Leonardo's military projects, it was a detailed concept rather than a documented battlefield machine.

A giant crossbow is not the same as a ballista or a trebuchet. A crossbow stores energy by bending a bow, while a trebuchet uses a pivoting arm and counterweight. Leonardo's drawing adapts the crossbow principle to an exceptionally large siege weapon.