The Guidestones

Monolithic stones set in place with instructions for the civilization that comes after ours:

The strangest monument in America looms over a barren knoll in northeastern Georgia. Five massive slabs of polished granite rise out of the earth in a star pattern. The rocks are each 16 feet tall, with four of them weighing more than 20 tons apiece. Together they support a 25,000-pound capstone. Approaching the edifice, it's hard not to think immediately of England's Stonehenge or possibly the ominous monolith from 2001: A Space Odyssey. Built in 1980, these pale gray rocks are quietly awaiting the end of the world as we know it.

Called the Georgia Guidestones, the monument is a mystery—nobody knows exactly who commissioned it or why. The only clues to its origin are on a nearby plaque on the ground—which gives the dimensions and explains a series of intricate notches and holes that correspond to the movements of the sun and stars—and the "guides" themselves, directives carved into the rocks. These instructions appear in eight languages ranging from English to Swahili and reflect a peculiar New Age ideology. Some are vaguely eugenic (guide reproduction wisely—improving fitness and diversity); others prescribe standard-issue hippie mysticism (prize truth—beauty—love—seeking harmony with the infinite).

I'm fascinated by the idea that someone actually went ahead and took the massive effort to build this monument. Instead of some general messages, I would have preferred some actual advice however. How to build a hut or a spear or how to make fire or something--skills without which some higher guidelines to rebuild Earth are not much use anyway, when the local mutant animals start wiping out you and the other survivors.

American Stonehenge: Monumental Instructions for the Post-Apocalypse