A network of Native American ceremonial and burial mounds in southern Ohio have been added to the list of world heritage sites of the United Nations Educational, Scientific and Cultural Organization (Unesco). The move places what the organization describes as “part cathedral, part cemetery and part astronomical observatory” on the same cultural plane as the Acropolis, Machu Picchu, the Taj Mahal, Stonehenge and the Great Wall of China.
The recognition of the Hopewell ceremonial earthworks was announced by Unesco’s world heritage committee during a meeting in Saudi Arabia.
The US Department of the Interior had last year proposed adding the earthworks to the world heritage sites list after a lengthy campaign by Indigenous tribes – many with ancestral ties to the state – and preservationists.
The Ohio history connection, a state agency, said the earthworks were exceptional for their “enormous scale, geometric precision and astronomical alignments” and described them as “masterpieces of human genius”. They encompass eight sites spread over 90 miles (145km) in southern Ohio.
Two years ago, the state’s supreme court heard a challenge over access to one part of the earthworks – a set of 2,000-year-old Octagon mounds – after an earlier ruling that the Ohio history connection could reclaim the site from a local golf club.
Chief Glenna Wallace, of the Eastern Shawnee Tribe of Oklahoma, said she greeted the Unesco designation for the mounds with “pure excitement and exhilaration”.
“Tears came to my eyes, and exhilaration turned into reflection, knowing that the world will now see and recognize the commitment, spirituality, imaginative artistry and knowledge of complex architecture to produce magnificent earthworks,” she said in a statement.
“Our ancestors were not just geniuses – they were uncommon geniuses,” she added.
The Hopewell site near Newark, Ohio, is part of eight large earthen enclosures built in a central and southern area of the state between about AD1 and AD400. They are considered to be the largest set of geometric enclosures in the world.
Other sites included under the new designation are the Fort Ancient earthworks in Oregonia and the Great Circle earthworks in Heath and five sites within the Hopewell Culture national historical park in Chillicothe: the Mound City group, the Hopewell mound group, the Seip earthworks, the High Bank earthworks and the Hopeton earthworks.
“Inscription on the World Heritage List will call international attention to these treasures long known to Ohioans,” Megan Wood, executive director and CEO of the Ohio history connection, said in a statement to the Columbus Dispatch.
The Octagon earthworks are believed to follow an 18.6-year moon cycle, with the central axis of the earthworks aligning with the northernmost rising of the moon, and other walls aligning with different moonrises.
In the 1970s, Ray Hively and Robert Horn, two professors at Ohio’s Earlham College, rediscovered the alignments and said the walls of the Octagon “define the most accurate astronomical alignments known in the prehistoric world”.
It is believed that the earthworks were host to ceremonies that drew people from across the US, based on archaeological discoveries of raw materials brought from as far west as the Rocky Mountains.
Earlier this year, Mike DeWine, the Ohio governor, called the anticipated Unesco designation “a big deal”.
People, he said, “will recognize that Ohio’s people – even in ancient times – played a pivotal role in transforming what is now Ohio into a sophisticated and prominent trading center”.
Audrey Azoulay, the Unesco director general, said the earthworks’ inclusion on the heritage list “will make this important part of American history known around the world”.
The addition of Hopewell comes just three months after the US rejoined Unesco. Azoulay said that the US now has 25 heritage sites on the world heritage list, “which illustrates the richness and diversity of the country’s cultural and natural heritage”.