Fifteen pyramids, plazas, ball game courts and tall stone sculptures comprise the ruins of an ancient Maya city recently discovered in the rainforests of eastern Mexico. The archaeologists that found the lost city say it remained a secret of the forest for centuries.

One of the pyramids stands 75 feet tall, according to Reuters, which also reported the city could have been home to as many as 40,000 people, likely during the late Classic period of Maya civilization between 600 and 900 A.D.

Ivan Sprajc, an associate professor at the Slovenian Academy of Sciences and Arts, spearheaded the discovery. He and his team named the city Chactun, which means "Red Rock" or "Large Rock." They first spotted the city when assessing aerial photographs of the nature reserve encompassing Chactun. It took the team three weeks to clear a 10-mile-long path through the forest to reach the site.

Sprajc told Reuters the whole site, which covers 54 acres (22 hectares), is one of the largest ever discovered in the Yucatan central lowlands. Chactun was unknown to the scientific community, but Sprajc did find evidence of other people being at the site two or three decades ago, but not since.

"Lumberjacks and gum extractors were certainly already there, because we saw cuts on the trees," Sprajc told Reuters. "What happened is they never told anyone."

Sprajc said the presence of ball game courts was an indication the ancient city was likely an important one, though it was probably abandoned around the year 1,000 A.D. due to civil unrest, demographic pressure and climate change.

Sprajc told Reuters he hopes the discovery will shed new light on the relations between different regions of the Maya civilization during the period.