I still need to do a road trip and go see those things. I first learned of them from a Wired magazine article half a dozen years ago.
http://archive.wired.com/science/discoveries/magazine/17-05/ff_guidestones
There is a semi interesting special aboout them in The History Channel show ‘” Decoded”
You can find it on YouTube..
Thanks for the link. Really interesting. One off topic though is how every small city in the south is the buckle of the Bible Belt. As for it’s withstanding a catastrophe, I think the great earthquake of Revelation will topple that little altar.