Quadripartite gothic vaults in Akoutstolith at the Riverside Church in New York City by the Guastavino Company. Today, it is impossible to tell that the completed nave of the Riverside Church is framed in steel (as seen here). The Guastavino Company was able to integrate its vaulting into the steel framing, so that the loads were shared between the two systems. Though this made the vaulting seem decorative rather than essential, the vaulting was in fact load bearing and part of the building's structural system. Courtesy of Avery Architectural and Fine Arts Library, Columbia University