White collaborated closely with Clarence Mackay's wife, Katharine Duer Mackay (1880–1930), and with her approval based the main façade of Harbor Hill upon that of François Mansart's Château de Maisons of 1642, using a mix of other influences to finish the overall design.

Built at great expense and furnished lavishly (at least three different decorating firms were employed), the home originally sat on 688 acres (2.78 km2) and enjoyed views across Roslyn Harbor to Long Island Sound.

Social events held at the house included a grand party for the then Prince of Wales (later Edward VIII and the Duke of Windsor) in 1924.

[3] On June 13, 1927, Charles Lindbergh, accompanied by his mother and the Mayor of New York, was feted at a banquet and dance Mackay held the night of transatlantic aviator's ticker-tape parade on 5th Avenue.

[6] After Harbor Hill was razed; a fountain with four equestrian statues designed by Henri-Léon Gréber was moved to Kansas City, Missouri, where it is displayed adjacent to Country Club Plaza.