St. Paul's Chapel at Columbia University is one of the earliest buildings designed by I. N. Phelps Stokes, an architect who had studied at Columbia and at the Ecole des Beaux-Arts in Paris. The spiral staircase was designed by the Guastavino Company and has served as the visual focal point, as well as a form of structural stability, for the chapel since. Photo © Michael Freeman. Courtesy of the Museum of the City of New York