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How did steel frames and curtain walls contribute to the International Style?

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The Great Court at the British Museum in London features a large central rotunda surrounded by wide steps and a glass and steel lattice roof, with visitors walking throughout the space. — Architecture The Great Court, designed by Foster and Partners, 2000; in the British Museum, London.

The International Style emerged in the 1920s and 1930s, defined by an architectural philosophy that prioritized function, structural honesty, and the elimination of nonstructural ornamentation. Steel frames and curtain walls were fundamental to this movement, as they allowed architects to move away from traditional, load-bearing masonry construction.

The use of steel skeletons provided a robust, efficient structural framework that supported the building's weight, effectively rendering heavy brick or stone walls obsolete as structural elements. This innovation enabled the creation of open interior spaces and rectilinear forms, which are hallmarks of the style. Because the steel frame carried the load, the exterior walls no longer needed to be thick or supportive; instead, they could be treated as light, taut, non-load-bearing skins.

Architects utilized this by applying glass curtain walls—sheathing the building in glass—to create a visually weightless quality and a clean, geometric appearance. By openly expressing the building's technical foundation through these materials, the International Style established a harmony between modern engineering, utility, and aesthetic discipline.1