GUATEMALA CITY (Reuters) - Thousands of previously unknown ancient Maya structures, including pyramids, palaces and causeways, have been revealed in Guatemala following an investigation by a team of international archaeologists using ground-penetrating laser technology.

The find allowed the researchers to map the outlines of what they describe as dozens of newly discovered Maya cities hidden under thick jungle foliage centuries after they were abandoned by their original inhabitants, according to a statement issued on Thursday by Guatemala’s PACUNAM foundation.

The ancient Maya civilization was one of the most advanced to arise in Mesoamerica, marked by sophisticated mathematics and engineering that allowed it to spread throughout present-day Central America and southern Mexico.

The research used so-called LIDAR technology that utilizes light from lasers to construct a detailed survey of buried structures.

“The fortified structures and large causeways reveal modifications to the natural landscape made by the Maya on a previously unimaginable scale,” said Francisco Estrada-Belli of Tulane University.

The team of archaeologists surveyed more than 810 square miles (2,100 sq km) of the Peten jungle and even revealed a pyramid in the heart of the ancient Maya city of Tikal, a major tourist destination in northeastern Guatemala.

The pyramid measures nearly 100 feet (30 meters) tall and was previously thought to be a small mountain.

The earliest Maya settlements were constructed around 1,000 B.C., and most major Maya cities collapsed by 900 A.D. The cause of the collapse remains the focus of intense academic debate.