Hardin County Illinois has 5 places on the National Register of Historic Places including 2 places of National significance and 1 place of Statewide significance. Significant places include Battery Rock, Orr-Herl Mound and Village Site and Rose Hotel, Cave-In-Rock and Illinois Iron Furnace.
Prehistoric cultural affiliation(s) include Mississippian dating back to 500.
Some of the country's most noteable architects helped create the Hardin County places including James McFarlan. Prominent architectural styles found in Hardin Country are Colonial and Georgian.