Middlesex County Connecticut (Vacant / Not In Use) has 8 places on the National Register of Historic Places including 1 place of National significance and 5 places of Statewide significance. Significant places include Rapallo Viaduct, Doane's Sawmill/Deep River Manufacturing Company, Metro South Historic District, Pratt, Read and Company Factory Complex and Starr Mill Road Bridge.
Some of the country's most noteable architects helped create the Middlesex County places including Edward W. Serrell, Phenix Iron Works, Charles M. Williams, Francis Kimball, Berlin Contruction Company and Buck & Sheldon Ford. Prominent architectural styles found in Middlesex Country are Colonial Revival, Federal and Greek Revival.