Ditto Knolls is a historic home and farm located near Hagerstown, Washington County, Maryland, United States. It was built about 1790, and is a five-bay, two-story brick house with a two-bay, one-story brick rear wing. It features a one-story entrance porch supported by Doric columns. Also on the property is a large stone bank barn and springhouse. It is one of two historic farm complexes located in Ditto Farm Regional Park, along with the Henry McCauley Farm.