Trumbull County Ohio (Historic Districts) has 8 places on the National Register of Historic Places including 1 place of National significance and 3 places of Statewide significance. Significant places include Mahoning Avenue Historic District (Boundary Increase), Gustavus Center Historic District, Mahoning Avenue Historic District and Mesopotamia Village District and Brookfield Center Historic District.
Some of the country's most noteable architects helped create the Trumbull County places including Isaac Ladd and Barton Brooke. Prominent architectural styles found in Trumbull Country are Federal, Greek Revival and Late Victorian.