41. The Guidestone of Life

Georgia’s own Stonehenge, the mysterious granite slabs known as the Georgia Guidestones, serve as a modern-day Rosetta Stone for the post-apocalyptic crowd. Ten guidelines for repopulation are etched in stone, yet the author remains as elusive as a ghost.

It’s the kind of thing that would make conspiracy theorists skip with joy and leave historians scratching their heads. A monument shrouded in anonymity, almost as if it was left by time travelers for a ‘just in case’ scenario. America’s cryptic note to the future, a choose-your-own-adventure for civilization, signed, sealed, but not delivered by anyone we can name.