I recently learned about the existence of stone-age ruins right here in New Hampshire. Angie and I took the short drive to Salem, NH near the Mass border to check them out. It was really cool! They've dated some of the ruins at 2,000 BC. There were complete chambers to walk through, which was really awesome.
Some archaeologists think they were built by visitors to the New World. I'm not so sure about that, but some of the chambers were slightly reminiscent of burial chambers we explored in Ireland from the same period:
After further research, I learned there are sites like this all over New England. I can't wait to go out and find my own!