The house has been surrounded by and has survived much history. Additions were made and later demolished, only to be rebuilt later. The name Mount Clare was spread to the nearby railroad “shops” and station that developed nearby. (Charles Carroll of Carrollton was a director of the new B&O Railroad, and he laid the first stone for the railroad.) The estate left the Carroll family in 1840, and it became a Union Army headquarters during the Civil War. Later it became a beer garden. Since 1890, it has been owned by the City of Baltimore, which developed the estate into a public park. Since 1917, the house itself has been administrated by the Maryland Chapter of The National Society of The Colonial Dames of America in the State of Maryland, which operates the house as a museum, outfitted with art and furnishings from the colonial period. Most of the objects there once belonged to the Carroll family.