How Did Mystery Hill Get Its Name?

Universe

The huge stone slab at Mystery Hill in New Hampshire has long been a puzzle. Who put it there? Why? And what was it used for?

The slab seems to be the top of a stone table, which may have been the scene of animal or human sacrifice. The grooves along the edge of the slab may have been where the blood drained off.

Directly below the stone table a maze of underground caves opens into a small chamber.
Anyone whispering in this hidden room can be heard very clearly above the ground.

It is possible that ancient priests controlled their people by "mysterious messages" from "mysterious sources", actually the words of the priests themselves in the hidden room.

But who these priests were, and what became of them is still a mystery, the mystery of Mystery Hill!