Designated October 16, 1990
Riverdale was founded in 1852 when a group of wealthy businessmen purchased the land and parceled it into seven estates. Five of these original homes survive, variously altered in the 19th and 20th centuries, as does much of the landscaping and topography. New homes were built as the estates were subdivided in the twentieth century, mainly 1930’s and 1950’s, often in the Colonial Revival style.