Miamisburg Mound is listed on the National Register of Historic Places. It is 65 feet tall and 800 feet in circumference. It contains 54,000 cubic yards of earth, which corresponds to the contents of more than 3,400 dump trucks.
Excavations conducted in 1869 revealed details of construction suggesting the Adena culture built the mound in several stages. The excavators found a layer of flat stones, overlapping like shingles on a roof, at a depth of 24 feet below the surface. At one point in its history, the mound had a stone facing. Monuments like Miamisburg Mound served as cemeteries for several generations of ancient Ohioans. They also may have marked the boundaries of tribal territories.
There were once an estimated 10,000 American Indian mounds and earthworks in the central Ohio Valley. Today, about 1,000 of those landmarks have survived through private landowners, local and state, and federal agencies dedicated to preserving these ancient ruins.
Many of the mounds that have been saved were of the conical variety and most of those have never been professionally investigated to determine their contents or age. Ones that have been investigated were determined to have been created 2,000 to 2,800 years ago.
It was thought that the mound was built in successive layers over multiple generations. When a leader died, they created a wood hut that contained the body. That hut would then be set ablaze and then covered over with a layer of soil. With each death, the mound grew taller and wider.
Around 400 AD, the people that created these mounds and earthworks, disappeared from Ohio. What happened to them remains a mystery that will probably never be resolved.