Evidence of man in Ohio goes back as far as 13,000 BC, with the first inhabitants after the last ice age most likely being Paleo-Indians who seemed to have disappeared after the Younger Days impact event . Later they were replaced by Archaic people who are referred to as Native Americans. The Archaic period has been seen as divided into Early, Middle and Late Archaic periods, it is thought of as the second (possibly) period of human occupation that took place 8,000 BC to 1,000 BC.. The Woodlands Period went from about 1,000 BC to 700 AD and included the Adena and Hopewell peoples who are sometimes referred to as the Mound Builders. Other cultures extended the Mound Builders period to about 1300 AD.
The list below is far from a complete list of prehistoric sites in Ohio. Finding a clovis point in a farm field from a Paleo-Indian roaming your land 11,000-15,000 may be more memorable than visiting any of the historical sites. Ohio is literally, littered with artifacts from early man. There are many private and public displays throughout the State of “field finds”, which are far from uncommon, yet today.
Hopewell Culture National Historical Park, 16062 State Route 104, Chillicothe, Ohio 45601.  A group of 23 earthen mounds built by the Hopewell culture, 200 BC to AD 500.
Adena Conical Burial Mound. AKA Campbell Mound State Memorial. 20 feet high - 100 feet in diameter. Close to 270 W and I 70 intersection in Columbus OH on Montgomery St. Woodlands Period about 1,000 BC - 700 AD.
The Pyramids at Marietta at Marietta OH. Little definative information. Hopewell culture 100 BC–AD 500
Moundbuilders Earthworks. This site covers most of Newark, Ohio. Two main areas have been preserved. One area is at the park where you will find an embankment that is 1,200 feet in diameter with earthen walls from 8 to 14 feet high enclosing a 26 acre area. The other more impressive site (Octagon Earthworks) has a golf course located in it with some efforts of preservation, there is an observation stand. Hopewell Indians (100 BC-AD 500)
Wright Earthworks, Newark OH  Wright Earthworks, located less than a block west of the SR 79 intersection at Grant St.in Newark, Licking County, Ohio. The earthwork remnants may be viewed from James Street, a short distance from Grant Street and the SR 79 interchange. Hopewell Indians (100 BC-AD 500}
Serpant Mound State Memorial, Peebles (Ohio),  OH. A serpentine effigy mound built by Adena Indians, approx. 20 feet wide and nearly 0.25 miles long. The effigy represents an uncoiling serpent. Quite an impressive sight. The museum houses artifacts, pottery, implements and models depicting the construction of the Mound. Adena (800 BC-AD 100)
Serpant Mound Illustration
SunWatch Indian Village/Archaeological Park, 2301 West River Road, Dayton , Ohio . 800-year-old village built by the Fort Ancient Indians.
Flint Ridge State Memorial 3 miles south of Cynthia (Ohio), near (south/east) Newark (Ohio) off of SR 668.  Flint Ridge is a restored prehistoric quarry pit with a museum that explains both the digging and shaping of flint. It is a site well worth the visit. There is a flint knap-in (teaching, exhibiting flint knapping, swap flint) every Labor Day week end. At the other end of the park there is a camping area that has a fossil swap the same week end.
Fort Ancient, 6123 St Rt. 350, Oregonia (Ohio) 45054.  18,000 feet of earthen walls built 2,000 years ago. There is 9,000 sq. foot museum, focusing on 15,000 years of the history of early man in the Ohio Valley.
Miamisburg Mound , one mile south of exit 44 - SR 725 - and three miles west of exit 42 off I-75, in Montgomery County. Miamisburg Mound is the largest conical burial mound in the state of Ohio and possibly in the eastern U. S., constructed by the Adena Indians (800 BC - AD 100) on a 100-foot-high bluff, the mound measures 877 feet in circumference. Originally more than 70 feet high.
Inscription Rock,  Kellys Island, Lake Erie. Pictographs by 17th century Erie Indians. Birds, animals humans, AD 1200 and 1600.
Leo Petroglyph State Memorial,  Leo Petroglyph is near the village of Leo, five miles northwest of Jackson, in Jackson Cnty. Off of U.S. Route 35 on County Road 28, left in Leo on Twp. Rd. 224. Fort Ancient Indians, AD 1000 and 1650.
These sacred sites have endured much over time and have diminished more since the white settlers showed up in The Ohio Valley, than any other time in history. One of the biggest enemies of these sites has been the invention of the cast-steel plow. Property owners have ignored the importance of the remnants of early man and have plowed over burial sites, mounds and artifacts without concern. The most common way of discovering artifacts today, is during the plowing of fields (field finds). This lack of care or respect for these monuments reflects badly on current inhabitants. One needs to reflect on today’s burial practices and how their remains may be treated in the future
There are fantastic exhibits throughout the State. This is a short list.
Hopewell Culture National Historical Park, 16062 State Route 104, Chillicothe, Ohio 45601. 
Flint Ridge State Memorial 3 miles south of Cynthia, Ohio, near (south/east) Newark (Ohio) off of SR 668. 
Lowe-Volk Park, 38 acre Nature Park, located on SR 598, 4 miles north of newer SR 30.  Annual Arrow Head Day brings out some of the best of the areas private collections.
Associations and societies
Archaeological Society of Ohio,  6478 Winchester Blvd., Suite 120, Canal Winchester, Ohio 43110 USA Phone:800-736-7815 This has been an excellent organization for over 50 years. They offer numerous publications on their site and have an annual meeting in Columbus, OH., March of each year. There is a basketball court size room full of education, artifacts and new discoveries from the past year. Most exhibits are from private collections and one of the few opportunities to view them. Very friendly crowd.