Gudbrandsdalen(go͝od`brändsdäl'ĕn), valley region of Oppland co., S central Norway. It extends c.100 mi (160 km) from the Dovrefjell southeastward to Lillehammer on Mjøsa lake. A rich agricultural and timber district, the valley is also a tourist area. The Lågan River, which traverses the valley, is a valuable source of hydroelectric power. The valley has long been an important trade route and a main invasion route through S Norway and has a rich history; many Gudbrandsdalen farmers trace their ancestry back to saga times. Much of the action in Ibsen's Peer Gynt is set there.
a wide valley on the upper reaches of the river Lågen, in southern Norway. Length (between the lakes Lesjaskogsvatn and Mjøsa), 230 km. It is surrounded by steep slopes that are forested in places. Large portions of the Oslo-Trondheim and Oslo-Ândalsnes highways and railroads pass through Gudbrandsdalen. Farming and dairy livestock raising are carried on in the valley.