Also called the Stone Spheres of the Diquís or simply “Las Balos” the Stone Spheres of Costa Rica remain one of the biggest mysteries in archaeology. The more than 300 spheres, which are almost perfectly round, were unearthed by workers clearing a field in the 1930s. They range in size and weigh up to 16 tons. They are amazing man-made creations, but no one really knows how or why they were made by an ancient indigenous culture. Some of the stones are on display at the National Museum of Costa Rica while others are in their original spots at the Finca 6 Museum and Archaeological Site in Palmar Sur.