Via Street Use (you want to click on this image to get the full impact):

This is an extreme closeup scan (2400 dpi) of a paint chip retrieved from the ruins of Belmont Art Park by Amy McKenzie earlier this year. The fragment is about 1cm thick, and appears to consist of about 150-200 layers of paint. (For a sense of scale, note the ridges of my fingerprint in the lower right.) This should give you an idea of the staggering number of pieces painted in this spot over the decades. The park used to be surrounded by one long wall covered with artwork, but that wall was illegally demolished by real estate developers earlier this year.

When I was about 11, we moved to a new house. My bedroom was a little 9×9′ square smothered in dark wood paneling. When we peeled off the paneling we found layers and layers of wallpaper; I had fun peeling, doodling, and “vandalizing” the walls before the painters came.