The Millstone Valley Agricultural District is a historic district located south of Millstone on the western side of the Millstone River along River Road / County Route 533 in Hillsborough Township, Somerset County, New Jersey. The district was added to the National Register of Historic Places on August 10, 1977. Contributing properties The Blackwell's Mills Farmhouse was built in the first quarter of the 19th century. The two and one half story building shows Federal style. The Brookie was built early to mid 19th century. It shows Greek Revival style. Gallery See also River Road Historic Rural District – adjacent historic district on the south, along River Road References External links Historic districts on the National Register of Historic Places in New Jersey National Register of Historic Places in Somerset County, New Jersey New Jersey Register of Historic Places Federal architecture in New Jersey Georgian architecture in New Jersey Greek Revival architecture in New Jersey Victorian architecture in New Jersey Hillsborough Township, New Jersey