Humans?
We have our local family graveyard about a tenth of a mile down the street from where we live. Years ago, my wife did some restoration work on the headstones there. Restored all of them to almost original. Moat are marble. Not sure what she used to clean them with, but they look great. Lots of my family history is buried right there. Back to the early 1800's.
I'm sure it's the same where you live, but you could stumble upon a forgotten graveyard walking in the woods here. Hell, I found a small lost community a quarter mile from my home. Full stone basements and all.
I'll see if I can find the restoration pics my wife took. It was years ago, so it may take me awhile.