The achievement of the Hopewell Culture, however, is not simply in creating large, precise shapes, which they did without the vantage point of hills for an aerial view. They also embedded a sort of hidden geometry within these structures. Until the mounds were measured and compared, it was thought that the builders didn't have any mathematical and geometrical sophistication, as there are no written records to testify to their level of knowledge. It was eventually discovered, however, that they made precise measurements across their earthworks and connected them in unsuspecting ways.
