This maze of man-made chambers, walls and ceremonial meeting places in Salem, New Hampshire is believed to the oldest man made building in the United States. It is widely known as America's Stonehenge. Was it built by Native Americans or early Europeans? If it is the latter, Europeans have been to North America thousands of years before Christopher Columbus did. If the former built it, it is very different from other settlements they built, and also have a very in depth understanding of astronomy.
