Leonardo da Vinci’s circular military vehicle is commonly called the armored car.
Leonardo designed it around 1487–1489 for Ludovico Sforza, the ruler of Milan. The machine had a conical, turtle-like shell made from wooden plates and was intended to carry several light cannons. Sloping armor would help deflect incoming projectiles while openings allowed the crew to fire outward.
The vehicle was meant to move with the help of internal cranks connected to wheels. Some modern analyses have noted that the surviving drawing contains a gear arrangement that would make the machine move backward if built exactly as shown. Historians debate whether this was a deliberate flaw, a drawing error, or a way to conceal the design.
Calling it a tank is convenient but somewhat misleading. It had armor and weapons, yet it was a Renaissance siege concept rather than a tracked, engine-powered tank.