The Hedmark Museum, also known as the Storhamar Barn, is one of Fehn's best known works and unique in Norwegian post-war architecture. The design of various parts of the new museum building and the exhibitions followed Sverre Fehn through long periods of his career. It started in 1967, when the archaeological excavations were completed. The then director of the museum, Per Martin Tvengsberg, had been a student of Fehn at the Oslo School of Architecture, and Fehn was commissioned to do an initial design.
The works on site started in 1969, the barn was finished in 1971 and the south wing with the auditorium in 1973. The exhibitions were completed under the new director Ragnar Pedersen, and were completed in 1980. The pavilions in the castle courtyard were completed in 2005.