Leonardo da Vinci’s conical armored military machine is known as an armored tank.
Leonardo designed the fighting vehicle in the late 15th century, probably for Ludovico Sforza, the Duke of Milan. Its sloped, conical cover was intended to deflect enemy projectiles, while a ring of guns allowed occupants to fire in several directions. The vehicle was to move through the coordinated effort of men turning internal cranks.
The machine was never built for Renaissance warfare. A famous drawing appears to contain a mechanical error: the cranks would make the wheels turn in opposite directions. Some historians think this may have been deliberate concealment, while others regard it as a design mistake or an unresolved problem.
Calling it a tank does not mean it was a modern tracked vehicle. Leonardo’s design had wheels and no engine, tracks, or turret. The modern tank emerged during the First World War, more than four centuries later, but Leonardo’s concept is remembered for combining armor, mobility, and onboard weapons.