Okay, this is just downright cool. I want trees on my roof.
Green Roofs in Norway have become a long-standing tradition. Love buildings just melding with the landscape. During the Viking and Middle Ages most houses had sod roofs, and in rural areas sod roofs were almost universal until the beginning of the 18th century. Tile roofs, which appeared much earlier in towns and on rural manors, gradually superseded sod roofs except in remote inland areas during the 19th century.