Many of SOM's postwar designs are recognized as icons of American modern architecture. The firm's most influential early project was Lever House, completed in 1952 to become the first International Style office building in New York City. Constructed of glass and steel at a time when Park Avenue was lined with masonry buildings, Lever House introduced a sleek modernist aesthetic that embodied the spirit of the times and influenced an entire generation of high-rise construction. As architectural historian Reyner Banham wrote in 1962, “It gave architectural expression to an age just as the age was being born ... Lever House was an uncontrollable success, imitated and sometimes understood all over the Americanized world, and one of the sights of New York”. In 1982, the New York City Landmarks Preservation Commission designated Lever House an official landmark.