Located on a hill overlooking downtown Lebanon, Glendower is one of the finest examples of residential Greek Revival architecture found in Ohio. This historic mansion was erected in 1845 and was given the name "Glendower" by its original owner, John Milton Williams, to honor the Welsh prince and hero Owen Glendower. The house has had other illustrious owners, most notably Durbin Ward, a distinguished attorney, statesman and Civil War general.

The mansion's exterior features include Ionic and Doric columns, classic carved cornices and porticoes and a hipped roof with a captain's walk. The stately interior provides a natural setting for many elegant Empire and Victorian furnishings from Warren County's past.

In 1940, Glendower became the first home of the Warren County Historical Society, which is now located in Harmon Hall, a block and a half from Glendower.