Hundreds of mysterious spheres lie beneath the Temple of the Feathered Serpent, an ancient six-level step pyramid just 30 miles from Mexico City.
The enigmatic spheres were found during an archaeological dig using a camera-equipped robot at one of the most important buildings in the pre-Hispanic city of Teotihuacan.
"They look like yellow spheres, but we do not know their meaning. It’s an unprecedented discovery," said Jorge Zavala, an archaeologist at Mexico’s National Anthropology and History Institute.
The Mesoamerican ruins of Teotihuacan, a World Heritage Site, represent one of the largest urban centers of the ancient world. Thought to have been established around 100 B.C., the pyramid-filled city had more than 100,000 inhabitants at its peak, but was abandoned for mysterious reasons around 700 A.D. — long before the Aztecs arrived in the 1300s. Read more.