What armored fighting vehicle did Leonardo da Vinci design around 1487?

Leonardo da Vinci designed an armored fighting vehicle around 1487 that is commonly called an armored tank.

His concept was a conical, turtle-like wooden vehicle covered with metal plates. A ring of light cannons projected through openings around the structure, allowing the occupants to fire in several directions while receiving protection from enemy weapons. The machine was intended to move using cranks turned by people inside.

The vehicle was never built for Renaissance warfare. Its design includes a famous apparent gearing problem: the internal arrangement, as usually drawn, would make the wheels turn in conflicting directions. Historians debate whether this was an error, a deliberate safeguard, or an incomplete drawing.

Leonardo’s machine was not a modern tank with an engine, tracks, and rotating turret. It was an early armored vehicle concept, combining mobility, protection, and artillery in one design.