Fehn was born at
Kongsberg in
Buskerud, Norway. He was the son of John Tryggve Fehn (1894–1981) and Sigrid Johnsen (1895–1985). He received his
architectural education at the
Oslo School of Architecture and Design in
Oslo. He entered his course of study in 1946 and graduated during 1949. Among other instructors, he studied under
Arne Korsmo (1900–1968). In 1949, Fehn and architect
Geir Grung (1926–1989) won the competition for the Museum Building for the Sandvig Collections at
Maihaugen in
Lillehammer Municipality. In 1950, Fehn joined PAGON (Progressive Architects Group Oslo, Norway). The group, which was led by Arne Korsmo, had the goal of implementing and promoting modern architecture. At the age of 34, Fehn gained international recognition for his design of the Norwegian Pavilion at the
1958 Brussels World Exhibition. He was a professor at
Oslo's School of Architecture from 1971 to 1995 and principal from 1986–1989. He additionally lectured throughout Europe including at
Paris,
Stuttgart and
Barcelona. He also lectured in the United States at the
Cranbrook Academy of Art in
Bloomfield Hills,
Michigan,
Cooper Union in
New York City and
Massachusetts Institute of Technology in
Boston. ==Projects==