For ten years, the firm became primarily known for their open-plan informal summer houses. McKim became best known as an exponent of Beaux-Arts architecture in styles of the American Renaissance, exemplified by the Boston Public Library (1888–95), and several works in New York City, including the Morningside Heights campus of Columbia University (1893), the University Club of New York (1899), the Pierpont Morgan Library (1903), New York Penn Station (1904–10), and The Butler Institute of American Art in Youngstown, Ohio (1919). He designed the Howard Mansion (1896) at Hyde Park, New York.