Found in the southeastern part of the Mexican state of Campeche, in the heart of the Yucatan peninsula, the cities were hidden in thick vegetation and hardly accessible.
"Aerial photographs helped us in locating the sites," expedition leader Ivan Sprajc, of the Research Center of the Slovenian Academy of Sciences and Arts (ZRC SAZU), said.
Sprajc and his team found the massive remains as they further explored the area around Chactun, a large Maya city discovered by the Slovenian archaeologist in 2013.
No other site has so far been located in this area, which extends over some 1800 square miles, between the so-called Rio Bec and Chenes regions, both known for their characteristic architectural styles fashioned during the Late and Terminal Classic periods, around 600 - 1000 A.D.
One of the cities featured an extraordinary facade with an entrance representing the open jaws of an earth monster.
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