curtain wall

In a building, an external, lightweight, non-loadbearing wall (either glazing or cladding) that is hung from a metal frame rather than built up from the ground like a brick wall; the framework it shields is usually of concrete or steel. Curtain walls are typically used in high-rise blocks, one of the earliest examples being the Reliance Building in Chicago (1890–94) by Daniel Burnham and John Wellborn Root. In medieval architecture, the term refers to the outer wall of a castle.

In the early 20th century, the curtain wall was developed in two buildings by Walter Gropius: the Model Factory, Deutsche Werkbund Exhibition, Cologne (1914), and the Bauhaus, Dessau (1925–26). Since World War II its use has spread dramatically, initially in the USA with iconic buildings such as the Lever House, New York (1952), by Skidmore, Owings & Merrill, and the Seagram building, New York (1956–59), by Mies van der Rohe.