What vehicle did Leonardo da Vinci design with a conical armored body and hidden wheels?

Leonardo da Vinci designed an armored fighting vehicle with a conical body and concealed wheels.

The machine appears in Leonardo's engineering studies from the late fifteenth century. Its sloped outer shell was intended to deflect incoming projectiles, while a ring of guns around the platform would allow the crew to fire in several directions. The vehicle was meant to be moved by cranks connected to its wheels.

The design was never built for Renaissance warfare. Its heavy armor would have made movement difficult, and the proposed gearing appears to contain a flaw that would prevent the wheels from turning correctly. Some writers have suggested that the flaw may have been deliberate, but there is no firm proof that Leonardo intentionally sabotaged the design.

It is often called a tank, but that modern term can mislead. Leonardo's machine had no engine, enclosed turret, or modern tracked system. “Armored fighting vehicle” more accurately describes the concept.