What defensive vehicle did Leonardo da Vinci design with a conical, turtle-like shell?

Leonardo da Vinci designed an armored vehicle with a conical, turtle-like shell.

The vehicle appears in Leonardo’s military studies from the late 15th century. Its sloped outer covering was intended to protect occupants from incoming projectiles, while guns projected through openings around the shell. The drawing shows a broad, low machine on wheels rather than a modern tank with a rotating turret.

Leonardo’s notes also describe the vehicle as moving by mechanisms connected to its wheels. Historians have debated whether an apparent gear arrangement would move the machine as drawn; the surviving design may contain an intentional flaw, a drafting error, or an unresolved mechanical problem.

Calling it a tank is a useful modern comparison, but it can create confusion. Leonardo’s vehicle had no engine, armor plate in the modern industrial sense, or battlefield demonstration. It was a Renaissance concept for protected mobile firepower.