What military machine did Leonardo da Vinci design with a circular armored body?

Leonardo da Vinci designed an armored vehicle with a circular, conical body.

In a drawing from about 1487, Leonardo showed a covered platform that could carry several men and fire weapons through openings in its protective shell. Sloping armor was intended to deflect attacks, while wheels and internal mechanisms were meant to move the vehicle across the ground.

The machine is commonly called Leonardo’s tank, but that modern label can be misleading. It was not a completed tank with a functioning engine, and historians debate whether the drawing contains a deliberate mechanical error. The crank and gear arrangement as drawn would prevent the wheels from turning in the intended direction.

Leonardo may have designed the vehicle as a proposal for military patron Ludovico Sforza. No contemporary evidence shows that it was built or used in battle. Its importance lies in the combination of armored protection, mobility, and onboard weapons.