Leonardo Da Vinci imagined this instrument, but it never became real until now

The 15th Century artist Leonardo Da Vinci dreamed up many inventions — from flying machines to military devices. But he also imagined many musical inventions, including the viola organista.

It's sort of a cross between a cello and a harpsichord. Da Vinci included his design for the instrument in his Codex Atlanticus nearly 500 years ago. But, apparently, a full-sized viola organista was never built. Until now.

Polish concert pianist Slawomir Zubrzycki spent three years building his viola organista. From the outside it looks like a baby grand piano. But inside, there are no hammered strings. Instead, four spinning wheels are wrapped in horse tail hair, like violin bows. To turn them, Zubrzycki pumps a pedal that's connected to a crankshaft.

Zubrzycki unveiled Da Vinci's invention — and played it — at a concert in Krakow, Poland, this past October.

And he says it's almost as if Da Vinci himself were talking to him through it.

"I don't know what Da Vinci would say about that, but the instrument is very expressive," Zubrzycki said. "When I want to make something, my instrument makes something more — like it's talking to me."

Another concert pianist in the audience in Krakow, Gabor Farkas, liked what he heard.

"One thing the piano is missing is that as soon as you hit one note, it dies," Farkas told the British newspaper The Daily Mail. "Here you can make a crescendo. It's the dream of all pianists!"