As a result, it has been heavily trafficked during and probably preceding historical times. Due to often hash weather and road conditions, it has also been a barrier and a risk to the traveller. But nowadays, E6 and the railway is almost never closed due to extreme weather (less frequent than once a year).
There are marked routes (summer) and (mostly unstaffed) cabins for hikers, but long trips, tough terrain and often hash weather makes this an area for the experienced hiker. But staying in the valleys aound the mountain, there are lot of nice and not-demanding day-trips with beautiful sceneries, an unique plant life, knowledge about local culture and a change to get a glimpse of parts of the animal life: May be a golden eagle soaring overhead, a muskox (keep your distance!) or if realy lucky a reindeer in the distance.
Most of the area has been protected as two National Parks combined with numerous protected areas. The National Parks are:
Dovrefjell has a very central role in Norwegian mythology, history and mind. The name on Trøndelag plus Northern Norway - "det Nordenfjeldske" reflects this: There was no need to include the name of the mountain - it was obvius that it was Dovrefjell. When Norway got its Constitution (1814) the first Parliament swore, after having signed the Constitution; "United and true until the mountains of Dovrefjell do crumble."
Several mountain inns were established in the Middle Ages to house pilgrims to Trondheim, officials and other travellers. Two of them are still inn servicen - see Sleep (Lodging).
Flora and fauna
If you arrive Norway by plane from abroad, all trains on Dovrebanen and all long-distance buses on E6 stops at Oslo Airport Gardermoen. (Do not go to Rygge or Torp if going to Dovrefjell, unless you want to stay over night in Oslo.)
Details - se Get around.
For individual travelers there are no feeds/permits needed. Just obey the park rules which for the ordinary hiker may be put very simple: Behave yourself! Organized trips, for instance guided tours, are not allowed without permission from the Park Authorities.
Biking is not allowed outside roads in the National Parks, neither are (of course!) use of motorized vehicles outside roads - the latter applies to all of Norway also outside protected areas.
E 136 and railway Raumabanen runs along the south-western edge from Dombås to Åndalsnes (and Molde/Ålesund), national highways R70 and R62 from Oppdal via Sunndalsøra to Molde along the northwestern edge, R29 from E6 at Hjerkinn via Folldal to Alvdal (R3) along the southeastern edge and R3 from Alvdal via Tynset to Ulsberg (E6) along the eastern edge.
By railway the following stations on Dovrebanen are good starting points (S to N): Dombås, Hjerkinn, Kongsvoll and Oppdal. At Dombås, the Raumabanen railway branches off to Åndalsnes, with Lesja, Lesjaverk, Bjorli and Åndalsnes as actual starting points. All trains are operated by Norwegian State Railways (NSB) .
By car or bus there are about 340 km from Oslo to Dombås along E6 and 80 km further to Oppdal.
From Dombås to Åndalsnes there is about 105 km along E136. From Oppdal one may take R70 westwards to Sunndalsøra (70 km) and further along R62 in direction of Molde. By own car or bike the trip along Aursjøvegen from Sunndalsøra to Eikesdalen over the mountains (no caravans!) is very impressive, further to Eresfjorden and R660 and R64 to Åndalsnes/Molde, or R660 to Eidsvågen (back on R62 between Sunndalsøra and Molde).
[Eastern part - later...]
As mentioned, the NSB operates the railways. All the roads mentioned above are operated by long-distance buses. Lavprisekspressen operates E6 solely (NB! you must book on Internet on beforehand!), Norway Bussekspress  operates on all the other roads mentioned avbove. (Exception is R 29, but there is a local bus meeting the trains at Hjerkinn along R29 going to and from Alvdal.)
[Many more, just added those two related to history paragraph!]