Almost perfectly round stone spheres, such as this one at a school in Palmar Norte, dot the Southern Zone of Costa Rica. (Courtesy Ifigenia Quintanilla)
- [/]

Costa Rica has made a bid for its spheres to be inducted into UNESCO's World Heritage list. (Courtesy Ifigenia Quintanilla)
- [/]

This is among the spheres that contain carvings that archaeologists have been researching. (Courtesy Ifigenia Quintanilla)
- [/]

A sphere in Hacienda Victoria in the Southern Zone. (Courtesy Ifigenia Quintanilla)
- [/]

A stone sphere sits in a park in the southern town of Palmar Sur. (Courtesy Ifigenia Quintanilla)
- [/]

Costa Rican archaeologist Francisco Corrales, left, UNESCO representative Nuria Sanz and Harvard University professor Jeffrey Quilter examine a specimen in situ during the recent sphere tour. (Courtesy National Museum)
- [/]