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The smaller dwellings only survive in traces of foundations, but the later civilisations built very sizeable structures in the forms of palaces, temples and ziggurats and took particular care to build them out of materials that last, which has ensured that very considerable parts have remained intact.
Major technical achievement is evidenced by the construction of great cities such as Uruk and Ur.
Built self-sufficiently by their inhabitants rather than by specialist builders, using locally available materials and traditional designs and methods which together are called vernacular architecture.
The very simplest shelters, tents, leave no traces.
Iron is not much harder than bronze but by adding carbon iron becomes steel which was being produced after about 300 BC.
Steel can be hardened and tempered producing a sharp, durable cutting edge.
For example, the first bridges made by humans were probably just wooden logs placed across a stream and later timber trackways.
In addition to living in caves and rock shelters, the first buildings were simple shelters, tents like the Inuit's tupiq, and huts sometimes built as pit-houses meant to suit the basic needs of protection from the elements and sometimes as fortifications for safety such as the crannog.
During the Bronze Age the corbelled arch came into use such as for beehive tombs.
History of building is evolving by different trends in time, marked by few key principles : durability of the materials used, the increasing of height and span, the degree of control exercised over the interior environment and finally the energy available to the construction process.
Neolithic, also known as the New Stone Age, was a time period roughly from 9000 BC to 5000 BC named because it was the last period of the age before wood working began.
In all cases of timber framed and log structures in these very early cultures, only the very lowest parts of the walls and post holes are unearthed in archaeological excavations, making reconstruction of the upper parts of these buildings largely conjectural.
Neolithic architecture ranges from the tent to the megalith (an arrangement of large stones) and rock-cut architecture which are frequently temples, tombs, and dwellings.The Ziggurat of Ur is an outstanding building of the period, despite major reconstruction work.