Occupying a half city block, the museum campus includes the main museum building, a log house, the MacDonell House (a Victorian mansion), a Shay Locomotive display, the Children's Discovery Center, genealogy and local history library, railroad archives, and the Children's Garden.

Originally located in Lima's Memorial Hall, the Historical Society outgrew the available space by 1935, and began privately raising funds to build a museum.

Spearheaded by Elizabeth M. MacDonell, and supported by the notable John Wesley Van Dyke, Chairman of the Atlantic Refining Company, the organization successfully raised the needed funds to build a separate facility.

World War II interrupted construction plans, but by 1954 the cornerstone was laid—a stone from the original White House, Washington, D.C.

After robbing banks in New Carlisle and Bluffton, Ohio, Dayton police captured Dillinger in August 1933 and delivered him to the Allen County Jail in Lima where he was held in connection to his crimes.

[4] The museum has a significant collection of Native American artifacts including art, pottery, clothing, arrowheads, and other remnants of the original inhabitants.

The largest collection of artifacts are from early and late modern history and show objects that were used in everyday life by the Native Americans.

The mock skeleton shows the ritual process of burying the individual in a flexed position with their legs drawn up against the upper torso.

The room in which the exhibit is displayed houses a variety of priceless artifacts including French Canton glassware used by Washington and his staff, busts of famous Americans, original pages from the ledger of King George III with the King's actual signatures affixed on the top, and an original 1795 American flag.

Perhaps the most unusual exhibit is its collection of over one hundred objects removed from the mouth, throat, or esophagus by doctors Walter and Estey Yingling.

The objects vary from coins, bones, teeth, buttons to larger pieces such as jewelry, bobby pins, a screw, keys, and a rubber hose.

[6] The Museum offers monthly lectures and programs, Traveling Trunks, demonstrations, and special events, including the annual Christmas Tree Festival.