 Skyscrapers of this period typically lost their ornamental horizontal divisions, being broken up by physical changes in their shape as one looked up the building, the whole forming a striking silhouette.In New York, the 1916 act to allow light and air to reach the streets encouraged a stepped or ziggurat approach to skyscraper design; this "set-back" style often made unrestricted use of the 25 percent of the site allowed by law to complete with a very tall tower.This encouraged a diversity of buildings, while maintaining an element of harmony and consistency of style.