The large enclosure at Marietta contained four flat-topped, rectangular platform mounds -- an unusual shape for this culture: the so-called Quadranaou Mound with four ramps, the Capitolium Mound with three ramps, another with two ramps, and a final un-ramped mound.

The Capitolium still stands on Fifth Street near Washington, near a gateway to the now-lost large enclosure. In 1918, the Capitolium was co-opted as the foundation of the new, Carnegie-funded Washington County Public Library, whose founders insisted this met the criterion of “public benefit,” as specified in the original earthworks preservation ordinance.

One if its three ramps carries the library’s front steps to the sidewalk. Another swells in the narrow yard behind. The best preserved ramp slopes to the alley, on the right side of the building. On the left side, the ancients designed only a kind of hollow between two lobes of earth – archaeologist Bill Pickard calls it an “anti-ramp.”

In 1990, when the library was adding an elevator in the “anti-ramp,” archaeologists were able to confirm that the mound was indeed from the Hopewell era. They also found a hearth, with charcoal from many different kinds of trees – most likely suggesting world-renewal rituals.