International Style is the 1932 codification of european modernism for an american audience — flat roofs, rectangular volumes, glass curtain walls, no ornament.
The International Style was named by the historians Henry-Russell Hitchcock and Philip Johnson in their 1932 catalogue and exhibition at the Museum of Modern Art, New York. They identified three core principles in the new European architecture: emphasis on volume rather than mass, regularity rather than symmetry, and an avoidance of applied ornament. The buildings they highlighted — by Le Corbusier, Mies van der Rohe, Gropius, J. J. P. Oud, Richard Neutra — shared a vocabulary of flat roofs, ribbon windows, white walls, and plan layouts driven by structural logic rather than historical convention. After World War II, the International Style became the default for American corporate skyscrapers: Lever House (1952), the Seagram Building (1958, by Mies van der Rohe and Philip Johnson), the Pan Am Building (1963). Critics from Lewis Mumford onward complained that the style had stripped European modernism of its socialist and humanist content; advocates argued it had produced an architecture that could speak across borders. The argument continues.