Gramercy Mansion is a historic mansion in Stevenson, Maryland, United States, located on Greenspring Valley Road near Stevenson University. It was built in 1902 by Alexander J. Cassatt, president of the Pennsylvania Railroad and brother of the American Impressionist painter, Mary Cassatt. Gramercy Mansion was presented as a wedding gift to Cassatt's daughter, Eliza. Later owners included the prominent Brewster family, one of whom became a Senator from Maryland. In the 1950s the estate became home to the Koinonia Foundation, a predecessor of the Peace Corps, before being bought and restored by Dr. & Mrs.