Until one hundred years ago, the skylines of the world's cities were characterized by silhouettes of trees and church towers, but as urban populations have grown, urban land has become extremely valuable. To keep up with the demands of the population but still provide affordable retail, office, and living space, builders have developed methods of constructing vertical rather than horizontal buildings.

The urban skyline began to experience change in 1883 when William Le Baron Jenney designed the first skeletal frame building, the Home Office Building in Chicago. Jenny's innovations opened the way for many other architects to literally soar to enormous heights. Among those moving in the direction Jenny had established were Louis Sullivan (1856-1924), William Holabird (1854-1923), and Daniel Burnham (1846-1912).

Many innovations occurred around the end of the nineteenth century that contributed to the success of the skyscraper. Rolled steel beams were introduced by the Butterfly Company...