This is the oldest building in Oslo. Built in the middle of the 12th century.

I stumbled on this by chance. Just wanted to go check out the national cemetery. Just so happens this church is right next to it...da. It was like 9 o'clock Sunday morning. Church service was at 11 o'clock. I could hear the choir practicing inside. I took a little video clip with my iPhone you can play it and hear the choir singing in this old church.