Magnolia Plantation, also known as the Boteler-Holder Farm, is a historic house and former slave plantation located at Knoxville, Washington County, Maryland, United States. It is a 2-story, five-bay-wide house built about 1835, with a 1 1/2-story three-bay rear addition, set on finely coursed local fieldstone foundations. Also on the property are several modern outbuildings and a barn, and nearby is a private cemetery with a number of grave markers bearing the name Boteler. The Magnolia Plantation was listed on the National Register of Historic Places in 1975.