Leonardo da Vinci designed an armored tank-like fighting vehicle with a conical cover and angled wheels. The machine appears in drawings made around 1487–1489 for military use.
The vehicle was a circular, turtle-shaped platform covered with armor plates. Several men inside would turn cranks connected to the wheels, allowing the platform to move and its mounted weapons to fire through openings. The angled armor was intended to deflect incoming projectiles, while the elevated profile offered a broad firing position.
It is often called Leonardo’s tank, but it was not a modern engine-powered tank. The design also contains a famous mechanical problem: the gearing as commonly drawn would make the wheels turn in opposite directions. Historians debate whether this was a deliberate error, a drafting mistake, or evidence that the design was not meant to be built exactly as shown.