Credit: John McLinden/Flickr
For as long as people have known how to write or draw and there have been buildings to write or draw on, there's been graffiti. One of the most fascinating things to see at Pompeii is the writing and drawing scratched into the walls of that doomed city, like this image here, which appears to be a caricature that a slave or servant drew of his master.
Today, despite police emphasis on the "broken window" theory of fighting nuisance crimes, graffiti is as prevalent as ever. And it reflects the times we live in: walk long enough around any city and you might just see some vandalism with a tech theme.