What Leonardo da Vinci invention was a large military weapon with a broad bow designed to hurl stones?

Leonardo da Vinci's giant crossbow was a large military weapon designed to hurl stones.

Leonardo drew the giant crossbow in the 1480s while working on military designs for the Duke of Milan. The machine had an exceptionally broad bow mounted on a wheeled frame. Its size was intended to create a powerful psychological effect as well as to launch large projectiles against enemy positions.

The drawing shows Leonardo thinking about mechanical advantage, transport, and battlefield spectacle. The weapon was a design study, not a confirmed battlefield machine. It is sometimes confused with Leonardo's catapult sketches, but the crossbow uses a bow-like flexible member, whereas a catapult uses an arm that pivots to throw a projectile.