Igloos can be attributed to the Innuit, native to the arctic regions of Canada, Greenland (remember, not green), and even the United States. The Innuit are commonly referred to as Eskimos.
Igloos were primarily constructed of ice but also employed whale bone. With temperatures in the region dropping as low as -49, Igloos were surprisingly efficient at utilizing body heat alone for warmth and could range from 19-61 degrees on the inside!
Igloos are different in construction from geodesic domes in that their components are built in an ascending upward spiral pattern, and if built properly can support the weight of a full-grown man. Unfortunately, they only offer limited protection from Polar Bears.