Leonardo da Vinci designed an armored tank as a covered military vehicle powered by people turning internal wheels.
His design, usually dated to about 1487, resembles a low, conical shell covered with metal plates. Several cannons project through openings around its perimeter, allowing it to fire in multiple directions while protecting its crew.
The vehicle was never built in Leonardo’s lifetime. A commonly repeated story says a deliberate gearing error made the machine unusable, but historians also discuss whether the apparent flaw resulted from interpreting the surviving drawing. Leonardo’s design was not a modern tank: it had no engine, tracks, or turret.
The concept belongs to a wider group of Renaissance military projects, including artillery, fortifications, and bridges. Modern reconstructions have shown that a working model can be made, although it requires changes to the wheel gearing and substantial human effort.