The Mona Lisa is hardly worth visiting anymore, both because of the security and because of the crowds.
Another tragedy of the same sort can be found at the Museum of Modern Art in New York. Van Gogh's "Starry Night," one of the great paintings of the 19th Century, is deliberately hung at shoulder level so that people can get photographs of it -- and not just photographs of the painting, but photographs of themselves WITH the painting. So they stand next to it, and give their cell phones to friends, who are not familiar with those cell phones, so it takes a while to make each photo as people fumble with unfamiliar equipment; the crowd is sometimes so intense that they are physically jostling each other around the painting. I'm amazed that no damage has yet been done to the painting. Really looking at it is impossible; a joke.
Art museums are now considered destination amusement parks, where you go to prove you got culture. Get your picture with Mickey, get your picture with Van Gogh, it's all the same. The Neue Museum in New York, which specializes in early 20th Century Austrian art (Schiele and Klimt), does not allow children under 12, and children under 16 must be accompanied by adults. It's a pleasure to visit. It's not the absence of children per se, that's critical, I don't think, it's the attitude -- this place is not an amusement park. When children are allowed to behave like children, as in the Modern, the adults do, too. Getting rid of children at museums is not the answer, but I think it should be made clear to them -- and to their supervisors, whether parents or teachers -- that if they start misbehaving, they'll be out on the street. In museums, children should be required to act somewhat like adults. They can do that, because I've seen it done; they're not there to see Mickey. If you go to the great Austrian museums, you see children...and they're just fine.
I do think cameras are at the center of this problem. I hate to ban them anywhere, but I really had enough of them in major museums. I think they should be banned, or their use should only be allowed with a permit.