Adena was the 5,000 acre estate of Thomas Worthington (1773-1827), sixth governor of Ohio and our state's first United States Senator. The mansion house, completed in 1807, is furnished today with antiques of the federal period, some of which belonged to Thomas Worthington himself. Situated on the 300 remaining acres are five out-buildings and the formal gardens. Looking east from the north lawn, one can see across the Scioto River Valley to the Mount Logan range of hills. This view is depicted on the Great Seal of the State of Ohio.

Adena is an important site for many reasons. It is the only plantation-type complex of its kind in our state. It is one of only three houses designed by Benjamin Latrobe still standing in the U.S. (Latrobe is considered the first professional American architect and served as Jefferson's surveyor of public buildings.) It is an original building, not a reconstruction. It is extremely well documented and that documentation was followed to the letter in the restoration. And, of course, it was the home of the Father of Ohio Statehood, Thomas Worthington, and was thus visited by many of the important political figures of the day.

Adena State Memorial, also known as Adena Mound, is an archaeological site located in Chillicothe, Ohio. It is one of the most famous and well-preserved examples of an Adena culture earthwork mound in the region. Here is a brief history of the site:

1. Adena Culture: The Adena culture was a prehistoric Native American culture that existed from around 1000 BCE to 200 BCE. They were known for their elaborate burial rituals and mound-building practices. The Adena people built earthworks, including burial mounds and circular enclosures, across several states, with a concentration in the Ohio River Valley.

2. Construction of the Mound: Adena State Memorial was constructed during the Middle Woodland period, around 800 BCE. The mound is conical in shape and stands approximately 20 feet tall with a diameter of about 85 feet. It was built using basket loads of dirt and clay, with the purpose of serving as a burial mound for high-ranking Adena individuals.

3. Rediscovery: The mound was rediscovered in the 1880s after being largely forgotten and overtaken by surrounding farms. It was initially excavated by Harlan I. Smith, a curator at the Smithsonian Institution, who discovered numerous burial remains, including artifacts made of copper, mica, and shells. The discoveries attracted significant attention and sparked interest in the Adena culture.

4. Preservation and Development: In 1891, Ohio established the Adena State Memorial Commission to acquire and protect the mound. The site was acquired and eventually turned into a state park. In the early 1900s, the state added a historic mansion near the mound called the Adena Mansion. The mansion, built by Thomas Worthington, is now a separate part of Adena State Memorial that offers tours and showcases early Ohio history.

5. Listed on National Register: Adena State Memorial was listed on the National Register of Historic Places in 1966, recognizing its significance and legacy. It is recognized as an important cultural and archaeological site, providing valuable insights into the lives and practices of the Adena people.

Today, visitors to Adena State Memorial can explore the awe-inspiring earthwork mound, visit the historic Adena Mansion, and learn about the Adena culture through exhibits and interpretive materials. The site serves as a testament to the rich heritage of Ohio's indigenous people and provides a unique glimpse into their past.