An underground tunnel that archaeologists believe was meant to imitate the underworld has been found under a pyramid at Teotihuacan in Mexico. Electrical scans taken at the ancient city revealed the extent of the mysterious tunnel.

"The finding confirms that Teotihuacans reproduced the same pattern of tunnels associated with their great monuments, whose function had to be the emulation of the underworld," archaeologist Veronica Ortega, who was involved in the discovery, said in a statement.

Hidden 10 meters (33 feet) beneath the ground, the tunnel extends from the Pyramid of the Moon, the second largest structure at the site, to the central square.

"The function of the tunnel may have been to reproduce the underworld, a world where life, animals and plants originated. It's possible that it was used purely for rituals, as part of ceremonies to celebrate the agricultural cycles," Ortega said.

The next step will be to get archaeologists into the tunnel to explore it up close. Researchers are hopeful that unlike a previous tunnel found at the site, the new one hasn’t been looted.

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Located north of Mexico City, Teotihuacan (meaning ‘the place where the gods were created’) was estimated to have once held a population of over 125,000 people. Built between the first and seventh centuries, before being abandoned around 550 AD, human remains at the site indicate it was used for human sacrifices.

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The tunnel was discovered in June, with details of it published by researchers at the National Institute of Anthropology and History in Mexico City on Tuesday.