Ancient Skulls
© PAU-INAHSome of the skulls mortared together in a circle.

Archaeologists have unearthed gruesome evidence of brutal rituals as they excavated what could be the largest ceremonial skull rack built by the Aztecs more than 500 years ago.

Found on the western side of what was once the Templo Mayor complex in Tenochtitlan, in modern Mexico City, the partially unearthed skull rack was likely built between 1485 and 1502 and may have been about 112 feet (34 meters) long and 40 feet (12 meters) wide.

Mostly belonging to young adult men, but also to women and children, several of the unearthed skulls feature holes on both sides, suggesting they belonged to a tzompantli. This was a rack on which the skulls of sacrificed people were arranged on wooden poles and displayed to inspire fear and awe.

To make the scene even more horrifying, the new finding revealed that part of the platform where the head rack once stood was made of rows of skulls mortared together in a circle.

All the skulls faced inward toward the center of the circle, although it's unknown what was in there.

"So far we have found 35 skulls, but there must be many more in underlying layers," archaeologist Raul Barrera of Mexico's National Institute of Anthropology and History (INAH) said in a statement.

According to Eduardo Matos Moctezuma, one of the INAH archaeologists involved in the ongoing excavation, the skulls would belong to the Huey Tzompantli, the Great Tzompantli of Tenochtitlan (modern Mexico City) which is estimated to have contained approximately 60,000 skulls.

"We believe we have found the Huey Tzompantli. Many of these skulls could be enemies of the Aztecs who were captured, killed and beheaded in a show of might," Matos Moctezuma said in a statement.