Following his acquisition in 1913 of the property at 1 East 91st Street in New York City from Andrew Carnegie, Kahn commissioned J. Armstrong Stenhouse and C. P. H. Gilbert to design his Carnegie Hill mansion. The home, an 80-room Italian Renaissance-palazzo style mansion, was modeled after the Cancelleria in Rome. Completed in 1918, it served as Kahn's New York City residence until his death. Shortly thereafter, the house was sold to the Convent of the Sacred Heart, an independent Catholic girls school. In 1974 the house was designated a landmark by the New York City Landmarks Preservation Commission.