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In architecture, construction, and real estate development the word building may refer to one of the following:
Any man-made structure used or intended for supporting or sheltering any use or continuous occupancy or 
An act of construction. 
To differentiate buildings and other structures that are not intended for continuous human occupancy, the latter are called nonbuilding structures.

The first artificial shelter on Earth is believed to be built 500,000 years ago by an ancient ancestor of humans