Leonardo da Vinci designed an armored tank-like fighting vehicle with a conical body.
His drawing from about 1487 shows a covered platform resembling a truncated cone. The sloping shell was intended to deflect enemy fire, while numerous small cannons projected through openings around the vehicle. Inside, men would turn cranks connected to wheels to move it across the battlefield.
The vehicle was never built for Renaissance warfare. Its proposed mechanism appears to contain a design problem that would make the wheels work against one another, although some historians have debated whether this was an intentional error or a drafting issue. The machine would also have been extremely heavy and difficult to maneuver.
Calling it a tank is modern shorthand. Leonardo’s vehicle was not a modern tracked tank and had no engine, turret, or enclosed crew compartment in the contemporary sense. It is better described as an armored fighting vehicle concept.