I can better that by a few thousand years. Egyption pyramids have graffiti tucked into corners, graffiti left by builders. I doubt there is any structure that doesnt have some improper mark left by someone during construction.
A nice example of this can be seen in the British Museum where one of the Assyrian Statues has a board game scratched into it's base, presumably by bored guards. There's a picture of it in this article http://www.bbc.co.uk/news/magazine-35669056
