... it is a National Park Site. And it is really old. Hopewell Culture is near Chillicothe, Ohio. There are actually several sites and at one time many more sites stretched across a wide area. These were constructed between 100BC and 1000AD. Once again a great ranger with interest in the subject at least allowed us to be impressed with the scope of these mounds. They are 10 to 25 feet tall and were surrounded by mound like walls. Some were burial mounds, some for ceremonial use but no one has enough knowledge to be certain. Nor is much more known about these early inhabitants. They did not live in large villages but very small family units and, apparently, came together for events here on occasions. There is also a mathematical precision to the size, shape and placement of the mounds that was mirrored across many sites. And that is quite a feat.