The windows of Oscars Church are often considered the church's greatest attraction. The 33 stained glass windows were created by the Norwegian artist Emanuel Vigeland and were added during the renovation of the church in the 1920s. Both technically and artistically, Vigeland was inspired by the medieval stained glass art found in the cathedrals of Italy and France. When Lars I. Wahlman was asked if he wanted to lead the transformation of the church interior, he set the condition that Vigeland would be commissioned to create the windows. This was accepted, and for three years, the artist worked in his glass studio outside Oslo on what would become the windows of Oscars Church.