An aerial survey in southern Mexico discovered a host of ceremonial sites that could date as far back as 1100 BC.
Extreme weather is rapidly eroding the limestone caves where people first drew images 40,000 years ago.
Archaeologists found the entrance to the unexplored burial shaft earlier this week.
Modern scholars have only been able to speculate about where the huge stones came from—until now.
The structure, believed to have served as a ceremonial center 3,000 years ago, was discovered in Tabasco, Mexico.