The prehistoric site at North Salem New Hampshire has as its main identification feature a sacrificial stone like those found in the Old World. Phoenician, 1000 BC. Human sacrifice? Maybe, the stone is big enough.
I have been through the site a couple of times and can see what they mean when they describe it as an alter. The place is strange and I have seen no convincing theories of who built it or why it was built.
The carbon dates (from a hearth within the ruins) for Mystery Hill are thousands of years old, which of course dumps on its ass the foolish notion that the megalithic site (which is quite large, and resembles the ancient hilltop mazes found in Europe and elsewhere) was a colonial root cellar. :')