Leonardo's mechanical knight is one of Leonardo's most memorable inventions. Most people would not believe that robots were possible in that time period, however Leonardo made that a reality. Though it was never actually physically built, the sketches in Leonardo's journals show that the robot had 3 main functions: to sit, to move it's arms, and to move it's jaw. Though those may not be too impressive compared to what we have in terms of robots now. In the renaissance it's a pretty big deal. If the invention had been built, or publically known, the invention and evolution of robots could have started all the way back then. Think of where we could've been now if they had!