Jotunheimen - literally the home of the giants - is the mountain massif of central Norway that holds the highest peaks in mainland Northern Europe. The range runs approximately 35 kilometers east-west and 25 kilometers north-south, sits at elevations of roughly 1,000 to 2,500 meters, and contains Norway's 26 highest peaks, including the country's highest summit, Galdhøpiggen at 2,469 meters. The range was given its current name in 1862 by the Norwegian poet Aasmund Olavsson Vinje, drawing on the Norse mythological term for the world of the giants in Old Norse cosmology.
Geographically, the Jotunheim landscape is a high inland massif of glaciated granite and gneiss, with active glaciers (Smørstabbreen, Jostedalsbreen's eastern arms), deep glacial lakes (Gjende, Bygdin, Bessvatnet), and dozens of named summits with technical alpine character. The trees stop at approximately 1,100 meters in the southern Jotunheim and well below that in the higher inner valleys. The weather is genuinely alpine and changes quickly; serious storms can develop within an hour at any time of the summer, and the standard Norwegian Mountain Code applies in full.
The classic visitor experience is hut-to-hut hiking - multi-day walking between staffed mountain lodges, some in the DNT network and some privately run. Gjendebu (built in 1871, DNT's oldest hut), Glitterheim, Gjendesheim and Fondsbu are DNT lodges; Memurubu, Spiterstulen and Krossbu are private lodges on the same trails. The best-known route is the 14-kilometer Besseggen ridge between Memurubu and Gjendesheim, high above two lakes of different colors, green Gjende and deep blue Bessvatnet. Most walkers take the boat from Gjendesheim to Memurubu and walk back, and UT.no reckons on about eight hours.
For travel planning, mid-July through early September is the most reliable window. June is quieter but the high passes can still hold late snow. September is exceptional in clear years - the colors turn, the crowds thin - but many of the high staffed huts close in the middle of the month. Both classic week-long hut-to-hut traverses and shorter base-hotel journeys with day walks fit Jotunheimen. See the long-form Sea to summit.