Harbor Hill was a large Long Island mansion built from 1899–1902 in Roslyn, New York, for telecommunications magnate Clarence Hungerford Mackay. It was designed by McKim, Mead & White, with Stanford White supervising the project - the largest private residence he ever designed. The home was built atop 348 feet (106 m) Harbor Hill, the highest point in Nassau County, New York, and demolished in 1949.