A recent aerial survey of the Maya Biosphere Reserve in Guatemala has uncovered a vast interconnected network of ancient cities, hidden for centuries beneath the jungle canopy that reclaimed this "megalopolis" after it was abandoned long ago. These new findings paint a picture of a far more complex and extensive pre-Columbian Mesoamerican civilization than what was previously assumed.

Using aircraft-borne LiDAR (Light Detection and Ranging) scanners, a team from the Foundation for Maya Cultural and Natural Heritage (Fundación Patrimonio Cultural y Natural Maya, or PACUNAM) created a 3D map covering 2,100 square kilometers (800 square miles) over 10 separate regions within the Maya Biosphere Reserve, revealing that previously-known Mayan cities such as Holmul, Tikal, Witzna, and Xmakabatun are vastly larger than what was previously assumed. The LiDAR scans, using laser pulses to see through the dense jungle canopy, uncovered a network of over 60,000 houses, palaces, elevated roadways, and fortifications–a civilization more on par with Ancient Greece or China than the culture of scattered settlements that modern archaeology previously thought.

"The LiDAR images make it clear that this entire region was a settlement system whose scale and population density had been grossly underestimated," explains Thomas Garrison, an Ithaca College archaeologist who specializes in using digital technology for archaeological research.

This new data has already yielded a large number of insights concerning the Mayan civilization: previously assumed to be home to roughly 5 million people at its peak between AD 250-900, the new map has tripled population estimates to 10 to 15 million, covering an area twice the size of medieval England, albeit with a much higher population density; the cities were interconnected with broad causeways that suggest a high volume of traffic, and were elevated to remain accessible during the rainy season; an interconnected system of canals and reservoirs also indicates a high level of civil engineering, delivering water to where it was needed during the dry season, and draining areas that required it when it rained.

The PACUNAM LiDAR Initiative is a three-year project that aims to map 14,000 square kilometers (5,000 square miles) of Guatemala’s lowlands, to uncover the secrets of the pre-Columbian settlement system that flourished there 1,200 years ago. "The ambition and the impact of this project is just incredible," said Kathryn Reese-Taylor, a specialist in Mayan archaeology with the University of Calgary. "After decades of combing through the forests, no archaeologists had stumbled across these sites. More importantly, we never had the big picture that this data set gives us. It really pulls back the veil and helps us see the civilization as the ancient Maya saw it."

The new LiDAR maps may also prompt archaeologists to re-think how civilizations are born and expand. "We’ve had this western conceit that complex civilizations can’t flourish in the tropics, that the tropics are where civilizations go to die," says Tulane University archaeologist Marcello Canuto. "But with the new LiDAR-based evidence from Central America and [Cambodia’s] Angkor Wat, we now have to consider that complex societies may have formed in the tropics and made their way outward from there."