Follow the inner ditch and notice the subtle gradations in the height and steepness of the wall. An excavation through the Great Circle wall has shown how the construction was done. First a set of point mounds were placed around in a circle. Then a ditch was dug, and that soil was used to make a ring. Finally, yellow gravelly clay was brought up from deep pits nearby, to cover the inside.

Building techniques probably had both spiritual and practical meaning: The yellow clay smoothed and supported the inner wall, but the color also made for a more dramatic ritual space. The ditch provided earth for the wall, but it also may have filled with water in wet seasons, presenting a second, magical circle.

Building the Newark complex 2000 years ago, they had to move more than 7 million cubic feet of earth. It would have taken many generations, or an enormous number of workers. Archaeologist Brad Lepper:

They were built with pointed digging sticks and perhaps hoes or picks, made with a deer shoulder blade, and hafted onto a stick – simple tools. The Hopewell people used this to dig pits in the ground and then fill the earth… in baskets and carry those baskets one at a time to mound them one after another.