Leonardo da Vinci designed an armored fighting vehicle commonly called a tank, with cannons pointing outward from its circular platform.
Leonardo drew the machine in the 1480s while working for Ludovico Sforza in Milan. Its conical, turtle-like wooden shell was intended to protect soldiers, and several light cannons were arranged around the vehicle so it could fire in multiple directions.
The design was powered by cranks connected to gears and was meant to be operated by people inside. A well-known problem is that the gear arrangement in the surviving drawing would make the vehicle difficult or impossible to move as shown. Some historians think this may have been an intentional mistake to keep the design from being used without Leonardo's permission.
Leonardo's vehicle was never built for a battlefield, and it was not a modern tank in the technological sense. Nevertheless, its armored body, mobile platform, and integrated guns make “tank” the standard short name for the invention.