Leonardo da Vinci's armored tank was a conical military vehicle surrounded by multiple cannons.
Leonardo designed the fighting vehicle around 1487 for the Duke of Milan, Ludovico Sforza. Its sloped, turtle-like cover was intended to deflect enemy fire, while cannons were arranged around the lower edge so the vehicle could fire in several directions. Inside, men were supposed to turn cranks connected to the wheels.
The design was never built for Renaissance warfare. A famous drawing contains a mechanical problem: the crank and wheel arrangements would make the vehicle difficult or impossible to drive as shown. Some historians think the flaw may have been deliberate, accidental, or simply an unresolved design issue.
Calling it a modern tank is convenient but not exact. It had armor, wheels, and weapons, yet lacked an engine and the tracked propulsion of later tanks. It remains one of Leonardo's best-known military engineering concepts.