[RightWhale]

The ruins at North Salem, NH seem to be 3000 years old and European. The round stone structure in Florida is fairly old, too, although I don't recall what the date was. The cave could be related. If there was one site, why couldn't there be more?

[hershey]

Exactly. If one site, why not more? Every time the house and land here in Harvard is sold, there's talk about closing it up so little kids won't go in and dislodge stones, hitting themselves in the head, but so far this cave is just there. People keep quiet about it, although anthropologists know it's there.

[blam]

"The round stone structure in Florida is fairly old, too, although I don't recall what the date was. "

If you're talking about the Miami Circle, it's only about 2,000 years old.