List of boroughs of Oslo
The 15 boroughs of Oslo were created on 1 January 2004. They each have an elected local council with limited responsibilities.
Local authorities call the current 15 bydeler also "District" in English. [1]
In addition is Marka (1585 residents), that is administered by several boroughs; and Sentrum (861 residents, 1.8 km2) that is partially administered by St. Hanshaugen, and in part directly by the city council. As of 1 January 2008, Oslo had 560,484 residents, of which 1134 were not allocated to a borough.
From 1973 to 30 June 1988, Oslo had 40 boroughs. Some existed only on paper, since they were to be constituted only when the areas were built.
From 1985 to 1988, the boroughs of Stovner, Røa, Gamle Oslo and Søndre Nordstrand were trials for the new system. From 1 July 1988 to 31 December 2003, Oslo had 25 boroughs:
In addition Sentrum and Marka.
...
Wikipedia