Image: Drawn by unknown artist based on sketches by C.F. Hall and photographed from the book by User:Finetooth / Public domain

Nobody knows who built the first igloo or when it was built but the indigenous people of the far north have probably been building them for tens of thousands of years. Igloos are constructed with snow, one of the weakest materials known, yet have incredible strength due to their self-supporting domed shape.

An Igloo is strong enough to withstand Arctic blizzards, lose half of its structure and remain standing, and is even strong enough to support the weight of a man standing on the roof. Igloos protect their inhabitants from the elements and are easy to build with a material abundantly provided by nature in the sparse northern regions.

Air pockets trapped in the snow blocks provide insulation and inside the igloo continuous melting and refreezing of the interior causes layers of ice to build on the inner walls, adding to the overall strength of the structure. The entrance is a tunnel that traps cold air in order to keep the living area warm. Igloos are a prime example of man's ingenuity to adapt to and use nature to his advantage.

Image: Momotarou2012 / CC BY-SA

Cultures from pre-history to modern times constructed domed dwellings using local materials. The earliest discovered may be four small dwellings made of Mammoth tusks and bones. The first was found by a farmer in Mezhirich, Ukraine, in 1965 while he was digging in his cellar and archaeologists unearthed three more. They date from 19,280 - 11,700 BC.

Discoveries of seal impressions in the ancient Chogha Mish (c. 6800 to 3000 BC), located in Iran, show the use of dome structures in mud-brick and adobe buildings. Other examples have been excavated at a Mesopotamian site of the Halaf (c. 6100 to 5400 BC) and Ubaid (ca. 5300 to 4000 BC) cultures.

The creation of dome-like structures has been documented among indigenous peoples around the world. The Wigwam by Native Americans uses branches covered with grass or hides. The Efé people of Africa construct similar structures using leaves as shingles.

Image: Max A. Khlopov / CC BY-SA

New production techniques allowed for cast iron and wrought iron to be produced both in larger quantities and at relatively low prices during the Industrial Revolution. Iron was used in place of wood where fire resistance was a priority. In Russia, which had large supplies of iron, some of the earliest examples of the material's architectural use can be found. Andrey Voronikhin built a large wrought iron dome over Kazan Cathedral in Saint Petersburg. Built between 1806 and 1811, the 17.7 meter wide outer dome of the cathedral was one of the earliest iron domes.