Rosalie Stier was a member of an aristocratic Belgian family that fled to the USA to avoid the effects of the French revolution. Her parents purchase land in Prince George's County, Maryland, and began to develop a plantation, Riversdale. Rosalie married George Calvert, whose father was a natural son of the fifth Lord Baltimore. The Stier family returned to Belgium to secure their property, and the Calverts moved into and completed Riversdale. It was their principal residence, although they owned several other properties. Rosalie managed the Stier's business affairs in the United States. Her numerous letters to them were preserved and collected into a book entitled Mistress of Riversdale. She had nine children, five of who lived to adulthood. Riversdale has been restored and is open to the public.