What armored land vehicle did Leonardo da Vinci design with a conical, shell-like cover?

Leonardo da Vinci designed an armored vehicle with a conical, shell-like cover and multiple cannons.

The machine appears in drawings from the 1480s, when Leonardo was seeking work at the court of Ludovico Sforza in Milan. Its sloped outer covering was intended to deflect incoming projectiles, while guns were arranged around the vehicle so they could fire in several directions. The crew would turn the wheels using internal cranks.

The vehicle is frequently called Leonardo’s tank, but it was not a modern tank. It had no engine, armor metallurgy was different, and the surviving design contains a mechanical problem: the wheel arrangement would tend to drive the vehicle in opposing directions. Some historians interpret that flaw as an error, while others have suggested it may have been deliberate.

No evidence shows that Leonardo’s armored vehicle was built or used in battle.