Across town from the Great Circle (once linked by ancient walled roadways, now by 21st Street, Main Street, and 33rd Street) the precise Octagon Earthworks present their perfectly level artificial horizons, used in antiquity to mark the complex movements of the moon. A giant circle connects via an avenue with the even larger octagon, with cleverly designed corner gateways. Small earthen walls nearby were the beginning of a long straight roadway to the southwest.

Arriving at the parking lot of the Moundbuilders Country Club, you are at the heart of the Octagon Earthworks. A small wooden platform has been built here to offer an orientation, and views into the Avenue connecting the giant Observatory Circle (on the left) with the open-cornered Octagon (on the right).

This octagon and its adjoining circle are the most precise of all the remaining earthworks. They’re a half-mile across, perfectly formed, and exactly level. The circle’s diameter is 1,054 feet, an interval that also perfectly constructs the Octagon (as the sides of a diagonal square it perfectly touches 4 gateways).

Avenue and gateway of the Octagon as seen from the Ohio Historical Society's elevated viewing platform.

Throughout the site, the walls are just at eye-level, keeping us enclosed, and forming an artificial horizon. Even the gateways are visually blocked by these smaller mounds. Inside this huge, perfect work of geometry, our eyes are drawn across from one point to another, and on to the real horizon beyond. Poles and banners probably marked the gateways. We can imagine grand processions along the wide roadways, moving among the various parts of the complex.

If golfers are not present (there are several “golf-free days” each year), walk the grounds thoroughly; it will take between one and two hours. Follow the giant circle to the left, as far as the Observatory Mound. From the top of this feature, ancient priests or shamans could observe the perfect alignment of the moon at its northernmost rising, appearing along the axis of the Avenue and across the center-point and distant gateway of the Octagon, about six-tenths of a mile away.

Precision of one of the walls of the Octagon, viewing toward the edge of the terrace above Raccoon Creek.




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