Byåsen is a district in the city of Trondheim, Norway. It constitutes a large part of the city encompasses a number of areas southwest of the city centre. This includes all areas on the west side of Nidelva and north of Granåsen. This is mainly a residential area, with 32,136 residents as of January 1, 2003. Gråkallbanen tram line connects Byåsen to the city centre along with a number of bus routes (8, 5, 19) as well as night time services by bus and tram in the weekends.
The name Byåsen can be translated into "city hill", which describes its elevated position, overlooking the rest of Trondheim. The view of Trondheim can be seen from Utsikten (meaning "the view") around which the wealthier residents of Byåsen live. House prices in the area are considerably higher than other parts of the city. Byåsen is the only larger district in Trondheim that have solid rock underground.
As a consequence of its position above the rest of the city (from 100–300 m above sea level) there is more snow on Byåsen during the winter than in lower parts of Trondheim. Bymarka, located on the southern and western part of Byåsen, is a large recreational area with forest and lakes, which is very popular for cross country skiing in the winter season. The weather conditions and the extensive network of cross country tracks in this area helped Granåsen, an outdoor winter sporting arena situated at the south end of Bymarka, in hosting the FIS Nordic World Ski Championships in 1997. Trondheim Golfklubb golf course is also based on Byåsen, although these same weather conditions complicate matters and shortens the season. There is also an 18-hole golf course located at Byneset in the western lowland area of Trondheim.
At the end of the last ice age, between 10,000 and 11,500 years ago, the sea level was about 175 meters higher than it is today. The old sea level is still visible in the landscape forming a line along the hill which can be seen from the city. This line is called the Strandline (Strandlinje) and is most easily spotted from Kristiansten Fortress which is located to the east of the city centre. A path following Strandlinje is today popular with visitors to the city forest area of Bymarka which covers the most elevated parts of Byåsen.