Look around any growing city, and it’s easy to see many types of buildings in various stages of construction. The tools and materials used today vary greatly from those used in the most primitive forms of construction, but the result is the same—a structure is designed and built to keep the inhabitants protected from the elements while providing a comfortable environment for them to live and work in.

The first signs of “construction” have been dated to the Neolithic period (the last part of the Stone Age), roughly 12,000 years ago. Structures were built from stone, wood, and mud, with a single “door” that was usually found at one end of the structure. An opening was sometimes created at the top of the structure so smoke could escape, but not every dwelling had one.