Wikipedia
Holmenkolbanen
A/S Holmenkolbanen was a company that owned and operated part of the Oslo Tramway and Oslo Metro in Norway from 1898 until 1975 when services were taken over by the majority owner Oslo Sporveier. Holmenkolbanen opened the Holmenkoll Line in 1898, and expanded it to become the first Nordic underground railway in 1928. The company took over operations of the Smestad Line in 1933, the Sognsvann Line in 1934. The company was merged into Oslo Sporveier in 1992.