American Stonehenge: Monumental Instructions for the Post-Apocalypse

http://www.wired.com/science/discoveries/magazine/17-05/ff_guidestones?currentPage=all# 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.