Leonardo da Vinci designed an armored vehicle as a circular fighting machine powered by eight men.
Leonardo sketched the vehicle around 1487–1490 while working for Ludovico Sforza, the Duke of Milan. Its conical cover was intended to deflect enemy fire, and the design included a ring of light cannons around the vehicle.
The vehicle was not built in Leonardo’s lifetime. Its movement depended on cranks connected to internal gears, with soldiers turning the machinery from inside the armored shell. Modern commentators sometimes call it a tank, but that label is retrospective: Leonardo’s design predates modern tanks by centuries and was never a practical battlefield vehicle.
A famous reconstruction problem is that the original gear arrangement appears unable to move correctly, possibly because Leonardo deliberately altered part of the drawing or because the design remained incomplete. The sketch is therefore best understood as a military engineering concept rather than a functioning prototype.