Squier and Davis’s map of Mound City also shows a huge circle, just to the south. Its remnants lie in the fields along Route 104. Now much degraded, its ghostly remnants are still visible in old aerial photos.

When the highway was widened recently, archaeologists investigated: The exterior ditch was originally twelve feet deep, and carefully lined with a foot-thick layer of clay – to hold the slopes, and water. Associated burials in the central mound suggest this monumental work was here before Mound City itself.

It’s probable that Shriver (circle) and Mound City (square) became prototypes for a new hybrid design at the Hopeton Earthworks (just across the river), and in turn led to all the geometrical experimentation and perfection found in the Paint Valley and at Newark and elsewhere throughout the Hopewell era.

Squier and Davis’s drawing of Mound City and the huge Shriver Circle in 1848, also showing the canal and the future Route 104.