Hopeton and High Bank are two major geometric earthworks that remain (though degraded) in the immediate Chillicothe area, now under the protection of Hopewell Culture National Historical Park (contact the park for possible or future visiting arrangements).

The linked circle and octagon at High Bank look remarkably similar to another pair at Newark, Ohio. Archaeologists are still investigating, but it seems the shapes are similarly connected to astronomical events. The crossaxis of the octagon points to the northernmost rising of the moon. And one of the octagon walls points to the summer solstice sunrise. Between them, these two alignments determine the orientation, and the shape, of the octagon. More mysterious are the walls and circles that trail off to the southwest.

While Newark and High Bank are about 70 miles apart, they were designed using similar principles. Their circles share the same diameter, and each harmonizes with its octagon: at High Bank, points at the center of all eight sides of the octagon can be joined to form a circle of equal diameter.

Ray Hively and Robert Horn have shown that High Bank, like Newark, encodes all eight lunar standstills, plus the four solstices, while the axes of the two designs are exactly 90 degrees apart. The builders could not simply replicate Newark’s design, due to the difference in latitude, so had to create here another equally complex and subtle instrument.

High Bank Earthworks centers on an axial line that also connects two other giant earthworks over a distance of several miles.