Two lost ancient Mayan cities were recently discovered deep in a Mexican jungle, and archaeologists believe there are "dozens" more waiting to be uncovered in the region.

The discovery was made by examining aerial photographs of the southeastern Mexican jungle on the Yucatan peninsula, revealing the two cities of Lagunita and Tamchen.

The site was actually visited in the 1970s by the American archaeologist Eric Von Euw, however, the exact location of the city Lagunita remained lost until now.

"The information about Lagunita were vague and totally useless," expedition leader Ivan Sprajc, of the Research Center of the Slovenian Academy of Sciences and Arts, told Discovery News.

"In the jungle you can be as little as 600 feet from a large site and do not even suspect it might be there; small mounds are all over the place, but they give you no idea about where an urban center might be," he added.

Sprajc and archaeologists scoured 1,800 square miles (3,000 square km) of land, between the so-called Rio Bec and Chenes regions, before stumbling upon these extraordinary cities - located only 3.7 miles (6 km) apart. According to Sprajc, the two cities date back to the Late and Terminal Classic periods between 600 and1000 AD.

At each archaeological site, palace-like buildings, pyramids and plazas were found. One of the pyramids is almost 65 feet (20 meters) high.

But one of the most interesting discoveries was an entrance representing the open jaws of an earth monster.

"The entrance apparently symbolizes the entrance to a cave and to the underworld ... Someone entering through this doorway would have entered sacred precincts," Sprajc told Reuters.

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 centers of the two sites," he told Reuters, "that's only like downtown."

In order to determine the significance of these two cities, further research is needed, according to the archaeologists, but Sprajc and his team are ready to start excavations on the site.