Back in '79, a well dressed man, identifying himself only as R.C. Christian walked into a granite finisher in Georgia, and laid plans for one of the most impressive monuments in the continental United States.
Supremely astrologically oriented, and carved with 10 helpful hints to surviving the apocalypse, it's a very impressive thing indeed. The monument gives advice like: "Keep the population under 500,000,000" and lots of caveats to "Find a balance with nature", as well as placing huge values on "Truth, Beauty, and Love".
There are lots of speculative claims about the monuments, not the least of which they are a manifesto for the "New World Order", put up by a "Luciferian Secret Society", or that they will be ground zero for an alien landing.
In any case, I really want to see the monument.
Wired article here.