Archaeologists have discovered five chambers at the 5,000-year-old site on the Orkney Islands, two of which have been partially excavated, the BBC reported Thursday.
Bones found carefully placed in gaps in the stones inside the chambers suggest the ancient burial site has never been disturbed, the say.
Orkney contains some of the best-preserved Neolithic remains in Europe and the new find is a "once-in-a-lifetime opportunity" to look at a Neolithic community, Orkney Islands Council's archaeologist Julie Gibson says.
The find is the first undisturbed burial of a Neolithic community to be uncovered in Scotland in 30 years.
"Science has moved on a lot in the last few years," Gibson said.
"It is now possible to find out where someone grew up, for instance. And in the case of the Amesbury Archer, found near Stonehenge, it could be seen that he had traveled from the Alps," she said. "It is by no means certain that all the people in this tomb will have been born here."