From Earth - Hjörleifur Stefansson

The first inhabitants of Iceland built their homes from the material that was closest at hand: the earth itself. In the early 20th century, more than half the Icelandic population were still living in turf houses, and a few dozen such buildings remain standing today. Icelanders were not the only northern nation, however, who built their homes of turf and rock: in the North Atlantic region, people were living in earth structures as recently as the early 20th century, although no trace of them remains today except in Iceland.The Icelandic turf house is a remarkable phenomenon in world architectural history. It is part of international cultural heritage, and one of Iceland’s most important contributions to global culture.