[sandworm101]

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.

[PJDK]

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

[Baeocystin]

I used to work as a welder in a shipyard. Deep in the hold, ribs never to be seen- dicks everywhere. It was almost poetic.