The history of the Oslo Tramway and Oslo Metro in Oslo (Kristiania until 1925), Norway, starts in 1875, when Kristiania Sporveisselskab (KSS) opened two horsecar lines through the city centre. In 1894, Kristiania Elektriske Sporvei (KES) built the first electric street tramways, which ran west from the city centre. Within six years, all tramways were electric. The city council established Kristiania Kommunale Sporveie (KKS) in 1899, which built three lines before it was sold to KSS six years later. Both KSS and KES were taken over by the municipality in 1924, becoming Oslo Sporveier. The company gradually expanded the city tram network, which reached its peak length in 1939.