A giant letter Z is carved into a Mexican hillside, evoking the mark of a legendary outlaw, Zorro; a strange sighting in Germany points to secrets from the Cold War; massive, blood-red marks in China prompt fears of a violent government crackdown.

An amateur archaeologist finds strange symbols scratched into the Kazakhstan desert; CIA surveillance photographs show what appears to be a giant Star of David on the island of Cuba; a lake in the Brazilian rain forest turns bright pink.