He was one of the most influential architects of the second half of the 20th century in Europe. He graduated from the Academy of Fine Arts in Vienna in 1956, continued his studies at the Illinois Institute of Technology with Mies van der Rohe in 1958/59, and the following year at the College of Environmental Design at the University of California. He worked in various architectural firms in Sweden and the United States before returning to Vienna, where he opened his own firm in 1964. In 1967 he signed the manifesto Alles ist Architektur (Everything is Architecture) with Walter Pichler, in which he expressed his desire to design using criteria taken from the world of the arts: from furniture design to housing construction, including urban planning as urban design. His projects include the Retti candle shop (1965), the Schullin jewellery store (1972–1974) and the Abteiberg Museum in Mönchengladbach (1972–1982). His teaching activity ran parallel to his professional career; he was a professor and from 1995 to 1999 dean of the architecture department at the University of Applied Arts Vienna. In 1985 he was awarded the Pritzker Prize. In the 1980s he also collaborated with Poltronova on the creation of the Mitzi and Marilyn sofas, as well as undertaking commissions for Alessi, Munari, Memphis MID and others. He was director of the architecture section of the Venice Biennale from 1994-1996.