Mona Lisa, why is it considered to be greatest painting ever ?

It is NOT considered "the greatest painting ever," you are misinformed.

It IS considered the most FAMOUS painting, ever. And that is not due to the painting itself, but due to it being stolen back in 1911. Very few artworks from the time of Leonardo have survived time. When the Mona Lisa was stolen, it brought the painting into the consciousness of people the word over, and that 'fame' has made it easily recognizable almost anywhere in the world today.

There is nothing specifically innovative or spectacular about the painting. It's fame comes from its age and notoriety. "Greatness" has nothing to do with it.

It was the first painting which used the technique invented by Leonardo da Vinci, which makes the eyes 'follow you round the room'.

It is one of the oldest surviving ~oil~ paintings. It's by DaVinci and there's not much real work surviving by him. And it is that sort of crusty, somber dark brown sort of work that art historians love so much. I don't thing anybody actually believes it's the greatest painting ever, just one of the most famous.

we are capitalists we haven't a clue Van Gogh was crap to his peers were they the idiots or us one is if so what is art who defines it half a dead cow in formaldehyde was hanging in the Tate Gallery a lot of people like trump a lot hate the sight of him history will say he was president the best a nation could offer of course supporters define the kings new clothes and you will have them Da Vinci did lots of things