The stone spheres of Costa Rica are a collection of over three hundred petrospheres in the Diquis Delta and on Isla del Caño of Costa Rica. Known locally as Las Bolas, they are also called The Diquis Spheres and stone balls of Costa Rica. These are the best-known stone sculptures of the Isthmo-Colombian area.
The spheres were discovered in the 1930s as the United Fruit Company was clearing jungle for banana plantations. Workmen pushed them aside with bulldozers and heavy equipment, damaging some spheres. Additionally, inspired by stories of hidden gold workmen began to drill holes into the spheres and blow them open with sticks of dynamite. Several of the spheres were destroyed before authorities intervened. Some of the dynamited spheres have been reassembled and are currently on display at the National Museum in San José.
The first scientific investigation of the spheres was undertaken shortly after their discovery by Doris Stone, a daughter of a United Fruit Co. executive. These were published in 1943 in American Antiquity, attracting the attention of Dr. Samuel Lothrop of the Peabody Museum at Harvard University. In 1948, he and his wife attempted to excavate an unrelated archaeological site in the northern region of Costa Rica. The government of the time had disbanded its professional army, and the resulting civil unrest threatened the security of Lothrop's team. In San José he met Doris Stone, who directed the group toward the Diquís Delta region in the South-West and provided them with valuable dig sites and personal contacts. Lothrop's findings were published in Archaeology of the Diquís Delta, Costa Rica 1963.