What armored vehicle did Leonardo da Vinci design with conical cannon-covered walls and wheels?

Leonardo da Vinci designed an armored vehicle commonly called Leonardo's fighting vehicle.

He drew the design around 1487 in the Codex Atlanticus. The vehicle has a conical, turtle-like cover with sloping armor intended to deflect projectiles. Several light cannons are shown around its lower edge, allowing it to fire in multiple directions.

The machine was meant to be moved by people turning cranks connected to wheels. A frequently repeated modern claim says the design contained a deliberate flaw because the gears would turn in opposite directions. Historians have debated whether this was an intentional safeguard, a drawing error, or simply an incomplete design.

The vehicle was never built by Leonardo for warfare. It belongs to a group of Renaissance military concepts that also included bridges, artillery ideas, and defensive machines. Its importance is mainly historical: it shows Leonardo applying geometry, mechanics, armor, and battlefield tactics to one proposed machine.