The stones were placed and carved so that they would be slightly inclined and perfectly adjusted to each other. Each block has to fit exactly with the others, and each block supports the others. All the stones are locked into one another and embedded into the bedrock.”

A unique feature of the monument revealed by the study showed how the upright stones were initially embedded, likely with the use of a counterweight, into foundation sockets so deep that up to one-third of the stones would have been below ground when first erected.

Once the walls had been completed, the builders placed five huge capstones to form the roof. The builders subsequently removed the earth to the desired floor level, erecting stone pillars for extra support.

“Once the capstones were added, it was like a solid box, with the bedrock still inside, and then they carved away all that rock, all that bedrock, to make the chamber,”