La Salle County Illinois (Historic Districts) has 8 places on the National Register of Historic Places including 4 places of National significance and 1 place of Statewide significance. Significant places include Marseilles Lock and Dam Historic District, Starved Rock Lock and Dam Historic District, Washington Park Historic District, Westclox Manufacturing Plant Historic District and Marseilles Hydro Plant.
Some of the country's most noteable architects helped create the La Salle County places including Walter Mickle Smith, Victor Andre Matteson and C.W. Humphrey. Prominent architectural styles found in La Salle Country are Classical Revival, Early Commercial and Italianate.