Costa Rica's newest UNESCO Heritage site is the stone balls, or Diquís Spheres. There are over 300 of these mysterious, near-perfect, carved spheres that range in height from a few centimeters to over 6 feet tall.
No one really knows, but they are believed to have been created around the year 600. Some people say that they came from Atlantis, others say that the people who made them had potions that allowed them to soften rock. Or maybe they were cannonballs of the gods.