The name "skyscrapers" is a coined word for a modern building of great height, constructed on a steel skeleton. It originated in
and many mechanical and structural development sin the last quarter of the 19th century contributed to its evolution. With the perfecting of high-speed electric elevators, skyscrapers were free to attain any desired heights. The earliest tall buildings were of solid masonry construction with the thick walls of the lower stories requiring an enormous amount of floor space. As greater heights were planned, the need arose for a form of construction that would permit thinner walls through the entire height of the building. Architects began to use cast iron with masonry, and this was followed by cage construction, in which the iron frame supported the floors and the masonry walls bore their own weight. The next step was invention of a system in which the metal framework would support not only the floors but also the walls. This was designed by William Le Baron Jenny in 1883, in the Home Insurance Building in Chicago. It was the first building in the world that employed steel skeleton construction and resembled a modern skyscraper. A number of other similar constructions followed, making Chicago the birthplace of the early skyscrapers. In the 1890's, the steel frame was developed into its final form, that of a completely riveted skeleton bearing all the structural loads, with the exterior or thin curtain walls serving merely as an enclosing screen. There followed a period of numerous experiments in in devising efficient floor plans and in seeking a satisfying architectural form. In 1916, city adopted the Building Zone Resolution, establishing legal control over the height and plan of buildings and over the factors relating to health, fire hazard, and assurance of adequate light and air to buildings and streets. Regulations regarding the setting back of exterior walls above a determined height gave rise to the setback buildings whose stepped profiles characterize the contemporary American skyscraper.