In the 1930s, workers from the United Fruit Company, clearing land in the Diquis Valley of Costa Rica, began unearthing large numbers of almost perfectly round stone spheres. The largest of these apparently man-made balls is over two meters in diameter and weighs over 16 tons. No one is sure exactly when or how they were made, or by whom, or for what reason, but, according to University of Kansas archeologist John Hoopes, “The balls were most likely made by reducing round boulders to a spherical shape through a combination of controlled fracture, pecking, and grinding.”
Today, virtually all of the spheres have been taken from their original locations. Many are prized lawn ornaments across Costa Rica. A collection of six now resides in the courtyard of Costa Rica's National Museum in San Jose.