The discovery was made at Pachacamac, one of the largest Prehispanic sites in South America, located on the Pacific Coast about 18 miles from Lima, Belgium's Universite libre de Bruxelles reported Tuesday.
In front of the Temple of Pachacamac, a scattering of later period burials was found to conceal an enormous burial chamber 65-feet long, dated to 1,000 years ago, that had survived the pillaging of the colonial period -- particularly intensive on the site -- and was intact, researchers said.
The oval tomb was covered with a roof of reeds supported by carved and shaped tree trunks.
A dozen newborns and infants were distributed around the perimeter, while the main chamber was separated into two sections separated by a wall of mud bricks that served as a base for yet more burials, archaeologists said.
Seventy skeletons and mummies were found inside those sections, representing both sexes and often accompanied by offerings including copper and gold artifacts, masks and ceramic vessels.
Pachacamac is a candidate for inclusion on the United Nations list of UNESCO World Heritage sites.