Archaeologists have found two ancient cities of the Mayan civilisation, and have dated them back to 600AD.
Lead researcher Ivan Sprajc, associate professor at the Research Centre of the Slovenian Academy of Sciences and Arts says there could be many more in the area. "There are dozens of sites that I already have seen on the aerial photographs."
The discovery was made by examining aerial photographs of the Mexican Jungle on the Yucatan peninsula, revealing the two cities of Lagunita and Tamchen.
An area of over 1,800 square miles around Chactun was explored. This site was first located and visited in the 1970s by Eric Von Euw, an American archaeologist. He documented details of the facade and other stone monuments with drawings.
However, the exact location of one of the cities, Lagunita as referred to by Von Euw was never found.
At each archaeological site, palace-like buildings, pyramids and plazas were found. One of the pyramids is almost 20m (65ft) high.
One of the most exciting discoveries is an entrance representing the open jaws of an earth monster.
"The monster-mouth facade represents a Maya earth deity related with fertility. These doorways symbolize the entrance to a cave and, in general, to the watery underworld, place of mythological origin of maize and abode of ancestors," Sprajc told Reuters.
Other discoveries include a number of huge palaces-like structures, a ball court and a temple pyramid with a height of 65 ft along with 10 stelae (tall sculpted stone shafts) and three altars were found. They featured well-preserved hieroglyphic inscriptions.
Sprajc said his team mapped 10-12 hectares (25-30 acres) at each site, but the cities were probably larger.
"We elaborated a map but only of the religious and administrative centres of the two sites," he said, "that's only like downtown."
His team have not yet excavated the sites, as further funding is need for this to take place.
Some speculate the Mayan civilization's mysterious decline in 900 A.D. was caused by overpopulation, endemic warfare, overuse of the land and environmental factors like severe drought, but the true cause remains unknown.