While he was involved in designing the furniture for the new headquarters in Dessau and buildings for the younger students, he began to experiment with tubular steel, apparently inspired by the structure of his new Adler bicycle. In 1929, he drew up the design for his most famous work, the B3 chair, better known as the Wassily chair. The structure is in tubular chrome-plated steel shaped into a single continuous and fluid line without joints or interruptions. The backrest, seat and armrests are made of eisengarn, an innovative fabric made rigid and resistant by applying wax and kerosene. Initially produced by the Standard-Möbel Lengyel company, founded by Breuer himself with his colleague Kálmán Lengyel, the chair passed to the Viennese Thonet, which bought out the company in 1929. Later produced by Gavina, this icon of design is now included in the Knoll catalogue.
After brief stints in Berlin and London, he settled in the United States, in Cambridge, Massachusetts, where he taught architecture at Harvard and founded an office with his mentor Walter Gropius. In 1946, he moved to New York, where he remained for the rest of his days. His career was divided between architectural and product design, reaching its peak in the 1950s and '60s, with such major projects as the UNESCO headquarters in Paris, in collaboration with Pier Luigi Nervi (1952). However, Breuer's fame remains linked primarily to his tubular steel furniture, iconic pieces that have never ceased production since their appearance in the 1920s and 30s. After various transfers of rights, today Breuer's furniture can be found in the catalogues of Knoll, (the aforementioned Wassily chair, and the famous embossed 1928 Cescaâ„¢ chair), and Thonet, which, in addition to its chairs, offers the S 285 desk collection (1935) and the S35 armchair and footstool collection (1929). He was the subject of the first monographic architecture exhibition organized by the Metropolitan Museum of Art in New York in 1975. Marcel Breuer retired the following year, bestowed with numerous awards and recognitions. He died at his home on East 63d Street in Manhattan in 1981.