Son of "Silver King" John W. Mackay, industrialist Clarence H. Mackay inherited his father's business interests and fortune. In 1898 he and his newlywed wife, Katherine Duer, obtained property in what is now the East Hills area of Roslyn, Long Island. Here, on the highest point in Nassau County, they erected a mansion called, "Harbor Hill." Designed by architect Stanford White, this elaborate mansion was torn down in the early 1950's to make way for a housing development.
The Mackay's and their estate had lasting impact on the Roslyn area. Photographs, news clippings, papers and documents are available for research in the library's Local History Collection.