Discuss what you think, in your opinion, is Da Vinci's greatest art work

Discuss what you think, in your opinion, is Da Vinci’s greatest art work

What I require is a personal essay: Discuss what you think, in your opinion, is Da Vinci’s greatest art work. Say something about this art work, its history, etc. And justify why you think it is his best work. Answer needs to be at least 300 words. Thanks!