An accomplished expression of the ideals of the midcentury-hegemonic International Style, and the most expensive office building ever constructed at the time of its opening, the Seagram building is all the more remarkable for having been designed co-operatively by two acclaimed architects, American Philip Johnson and German Mies van der Rohe. Like the United Nations headquarters and the Lever House, each completed earlier in the 50s, the Seagram building is as conventional an office building now as it was a radical structure when completed in 1958. A tall monolith of dull bronze, the building was meant to reveal its steel skeleton to the public, but New York building codes required that all steel be covered with fireproof material, and so, deciding the principle of functionalism was more important than actual functionalism, van der Rohe and Johnson decided to overlay the building's steel with bronze rather than a more traditional facade, giving an unfinished impression that suggested the building's skeleton was actually visible.