Marlboro Township, New Jersey has a number of historic sites. The Monmouth County Historic Site Inventory (HSI) was started in 1980 by the directors of both the Monmouth County Historical Association and the Monmouth County Park System. This inventory project provided an inventory number to all historic properties in Monmouth County, New Jersey. In addition to property details, this listing provides reference numbers for easy identification. In addition to the park system inventory, the Marlboro Township Historic Commission provides a listing of Historic Commission Landmarks (HCL). These are physical signs placed in historically significant locations. There was also a list presented by the NJ Department of Environmental Protection - Historic Preservation Office (HPO).