Why is the Mona Lisa considered so great? To me it is a routine painting of a plain woman.?

Technique. Sfumato and chiaroscuro. The dark, delicate sheer veil she is wearing on her dark hair.

Mystery. Who was she? Why was she smiling? Why does Vasari (next generation artist and art historian) describe her eye brows yet he'd never been to France in his life where painting was. If there were eyebrows, who removed them and was it on purpose or overaggressive cleaning? Who trimmed the canvas and when? Where is that odd landscape behind her or is that Leonardo's imagination?

History. Why did Leonardo keep it? Why did he work on it for the rest of his life? At his death, Leonardo willed it to France where he died. Napoleon had it in his bedroom. It was missing for a long time from the Louvre in the early 20th century.

Are you using Mona Lisa as a cover to refer to somebody that you might know?

What makes you think that she's a "plain woman"?

But although they say that "modesty is a virtue" it's also a bit dishonest for anyone to distort factual information.

One of the most overrated works of art in the world......