Green Roofs - a wise building technique

Green roofs are old, very old. They are being used thousands of years. In Scandinavia, according to what I`ve read until now, they exist especially in Norway (Sami people) and the Faroe Islands. The Vikings used to build houses with lawned roofs which causes a good interior climate. Also the legendary Hanging Gardens of Babylon tell about gardens upon houses.
In general, green roofs have many advantages. For example, they store water, so that water gets in contact with the roof much later, which can prevent damage on pipelines. The most obvious advantage is the prevention of extreme temperatures in the interior.

Sami house (source)

Earth lodge (source)

Faroe Islands (source)

Green Roof building by Zaha Hadid (source)

16th century coloured engraving of the Hanging Gardens of Babylon (source)