Ottawa County Ohio (Historic Districts) has 4 places on the National Register of Historic Places including 1 place of National significance. Significant places include Lakeside Historic District, East Point Manor, Main Street Historic District, Middle Bass Club Historic District.
Some of the country's most noteable architects helped create the Ottawa County places including J. Milton Dyer and Alfred Schnurr. Prominent architectural styles found in Ottawa Country are Chicago, Gothic and Italianate.