Gudbrandsdalen (dead link: January 2023) is a valley and traditional district in Oppland. This grand, central valley runs for some 250 km from Lillehammer to the uplands and central mountains. Nicknamed "the valley of valleys" because of its size and variety. In addition to the main valley there is a web of tributaries particularly from the west and the central mountains. The valley makes up more than half of Oppland county. Gudbrandsdalen is surrounded by the highest mountains in Scandinavia. The central mountains to the west create a long rain shadow leaving little precipitation for most of the area. Summers are pleasantly warm.
The valley hosted major events at the 1994 winter Olympics, alpine skiing venues at Kvitfjell and Hafjell are now popular winter sport resorts. The valley is home to a number of ancient wooden buildings (including stave churches) and other cultural heritage. Overland transport between Oslo and central eastern lowlands to Nordfjord, Trøndelag and Møre og Romsdal runs through the valley.
;Notable adjacent valleys (tributaries) in Gudbrandsdalen district:
Gudbrandsdalen stretches from Lillehammer at the northern shores of Lake Mjøsa to the higlands around Dombås and county border with Møre og Romsdal at Geiranger and Bjorli, about 250 km. At the watershed there is in fact a lake, Lesjaskogsvatnet at Lesjaskog, that is shared by Lågen river (flowing east) and Rauma river (flowing west to Åndalsnes). Gudbrandsdalen is home to the great Lågen river, Norway's second biggest. The Gudbrandsdalen district also includes several connected valleys and their tributaries (notably Ottdalen with Otta river, as well as Gausa, Sjoa and Vinstra rivers), large parts of Oppland county falls within this area. These tributaries are among Norway's prettiest and wildest rivers. Many of these rivers, particularly from the west (the right) carry glacial melt water, as can be seen on the opaque color. Hjerkinn and upper Folldal in the Dovre plateau has traditionally been affiliated with Gudbrandsdalen although rivers there flow east to Alvdal.
Gudbrandsdalen and adjacent valleys are surrounded by major mountain ranges such as Jotunheimen, Breheimen (next door to Jostedalsbreen), Reinheimen/Tafjord/Romsdalen, Dovrefjell and Rondane. At Otta the main valley is joined by the major Otta valley that also holds the road to Stryn and Geiranger. Because of its central position in the interior of South Norway, Gudbrandsdalen hosts E6 (the main north-south road with branch to Åndalsnes and Ålesund) and the Oslo-Trondheim railway (with arm to Åndalsnes). About 70,000 people live in the area, the regional centre Lillehammer is home to about half the population.
Gudbrandsdalen and tributary valleys is a traditional district. This area sits in the rain shadow and is one of the driest areas in Norway. The climate is mostly continental: winters are cold and summers are mild. Bjorli, the most north-western village, receives heavy snowfall and is a popular winter resort.
Henrik Ibsen, Norwegian playwright, hiked through the valley in 1862 and compiled material for dramas "Peer Gynt" as well as "Brand".
During the invasion of Norway in April 1940, some of the heaviest fighting occurred in Gudbrandsdalen around village Kvam. British troops had landed at Åndalsnes to support the Norwegian Army and with plans to recapture Trondheim. In addition to the sea battle at Narvik, this was the first engagement of Allied and German troops during the war (a few weeks later fighting began in France and Be-Ne-Lux). The British troops were not prepared for the task. There is a war memorial at Kvam. The first US casualty in world war II was the US military attache killed during the bombing of Dombås station. There is a war memorial at Dombås. The King, cabinet and Bank of Norway's gold and cash holdings were evacuated through Gudbrandsdalen towards Åndalsnes and Molde amidst heavy fighting in a bold and legendary operation. The king and the cabinet were hiding in Gudbrandsdalen while waiting for safe passage to unoccupied harbors at Åndalsnes and Molde. This was one of the most dramatic and decisive events in the history of modern Norway. British troops were evacuated on May 2. The failed British campaign in Gudbrandsdalen (and Namsos) led to the downfall of Neville Chamberlain as prime minister and Winston Churchill became prime minister.
Ironically, more than 300 years earlier Scottish mercenary troops landed at Åndalsnes and marched through Gudbrandsdalen to join the war in Sweden. Between Otta and Kvam the Scottish troops were slaughtered my local militia in a legendary ambush. This event is also included in the Kvam war memorial.
The language is Norwegian with some notable dialect differences, particularly in the northern valley. English is spoken everywhere.
See also E6 through Sweden and Norway
;By rail: The Oslo-Lillehammer-Trondheim railway (Dovrebanen) runs along the valley until Dombås where the railway climbs onto the Dovrefjell plateau. The Dombås-Åndalsnes railway (Raumabanen) continues along the northernmost section of the valley (Lesja-Bjorli area). There is no railway in the Otta-Lom-Skjåk valley (Ottadalen).
Gudbrandsdalen cuts deep into Norway's wilderness and as the big valley is also home to major rivers, including rivers popular among rafters. Warning: Only skilled rafters should go down rivers on their own. There are numerous obstacles such as power stations, rapids, canyons and waterfalls.