When I try to read about this I seem to always get these kind of canned responses praising the technical marvels of the painting but not an explanation of when it was first widely recognized as such and thus so highly valued.
I know most famously Van Gogh's art wasn't widely appreciated until at least a decade after his death, and people who saw his works before then weren't inherently awe struck as they claim to be now so clearly the famousness of a painting has to do with more than purely its technical merits. Does it just catch on like an Internet meme?
The 'canonicity' of certain works of art can often be attributed to the ways in which they have been treated by specific art historians. For example, the 'Girl With A Pearl Earring' by Johannes Vermeer, which is arguably as well-known and revered as the Mona Lisa, was a forgotten painting by an obscure Dutch artist until the 19th century French art critic Théophile Thoré-Bürger 'rediscovered' Vermeer, publishing a catalogue of his works (which over-attributed over 60 paintings to the artist, rather than the 34 which are accepted today). It was on the strength of this that the GWAPE was 'saved for the nation' when it was sold at auction in 1881, having been in the same private family collection for almost two centuries, and was ultimately bequeathed to the Mauritshuis museum. Entry into a museum or public collection also seems to be a key factor in determining the fame and importance of an artwork, because a degree of exposure is necessary in order for an image to become a cultural trope and permeate the public consciousness.
Hi, hopefully one of the art historians will drop by with a broader answer (and/or you might x-post to /r/arthistory), but for the case of the Mona Lisa anyway, you can get started on this interesting answer by /u/butforevernow
It’s cheesy, but most of the time the show’s on point.
Basically Mona Lisa was stolen, media went crazy, people figured it had to be this fantastic masterpiece for someone to actually steal it, everyone was talking about it, now its famous.
As for others, it really has to do with how much you see it (the more you see something, the more recognizable it is, the more likely you are to like it). Another reason would be rich people buying the art for their homes and talking about it; obviously if this rich person thinks it’s great it must be.