The Glass Chain or Crystal Chain sometimes known as the "Utopian Correspondence" () was a chain letter that took place between November 1919 and December 1920. It was a correspondence of architects that formed a basis of expressionist architecture in Germany. It was initiated by Bruno Taut. Names, pen-names, and locations of participants Bibliography Sharp, Dennis (1966). Modern Architecture and Expressionism. George Braziller: New York. Whyte, Iain Boyd ed. (1985). Crystal Chain Letters: Architectural Fantasies by Bruno Taut and His Circle. The MIT Press. External links Gläserne Kette, Sammlung im Hans-Scharoun-Archiv (in German), Academy of Arts, Berlin Die gläserne Kette collection, Canadian Centre for Architecture, Montreal, Quebec, Canada (digitized items) Expressionist architecture Architecture groups