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Ohio inventions and firsts · Achievement · 100 BCE-400 CE

Newark Octagon lunar alignment

The Hopewell-built Newark Octagon Earthworks (Newark/Heath, Licking County) align with the northernmost rising of the Moon in its 18.6-year cycle. Moundbuilders Country Club leased the site as a golf course from 1910 and left on January 1, 2025.

At a glance

Year
100 BCE-400 CE
Place
Newark, Licking County ZIP 43055 · Newark · Licking County

The story

The Hopewell people who built the Newark earthworks left no writing, so what they knew has to be read from the ground. The Octagon Earthworks cover about 50 acres with eight walls, each about 550 feet long, joined to a 20-acre circle called the Observatory Circle.

The Octagon works as a lunar observatory. The Moon's position at rising swings back and forth over a cycle of 18.6 years, and the site's lines follow that cycle. The Hopewell built the whole Newark complex between about 100 BCE and 400 CE, and the full complex once covered around 3,000 acres.

The nearby Great Circle in Heath is 1,200 feet across with walls up to 14 feet high and a moat 5 feet deep. A third part, the Wright Square, was nearly a perfect 20-acre square and was mostly destroyed by 19th-century development.

For generations a private country club leased the Octagon for golf. In 2022 the Ohio Supreme Court said the Ohio History Connection could use eminent domain, and a deal was reached in August 2024. In September 2023 the earthworks became part of the UNESCO listing.

Timeline

  • 100 BCE-400 CE: The Hopewell culture builds the Newark Earthworks. (Newark / Heath, OH) source
  • 2006: Newark Earthworks named Ohio's official prehistoric monument. (Newark, OH) source
  • 2022: The Ohio Supreme Court rules the history society may use eminent domain to take the country club's lease. (Columbus, OH) source
  • 2023-09: The earthworks join the UNESCO World Heritage listing. (Newark, OH) source
  • 2024-08: A deal is reached to end the golf lease. (Newark, OH) source

What it changed

  • The Octagon follows the Moon's 18.6-year cycle.
  • The site is part of a UNESCO World Heritage listing since 2023.

Why it matters

Evidence of astronomical knowledge.

Places in Ohio to see

Further reading

Sources

Confidence. Medium: the main facts were confirmed, but some details (often an address or ZIP code) were not.