The Observer has often wondered why many buildings in Manhattan have a ziggurat (step pyramid) configuration on the upper floors. Considering the expense of real estate in Gotham one would assume you’d build as straight and efficiently as possible. Aim for the stars, touch the sky, take the rent, reap the riches.
The answer lies in the Equitable building.
Upon its completion in 1915 the Equitable was the largest building in the world in terms of floor space. It rose almost 600 feet above Broadway and cast a shadow of over 7 acres. It’s immensity caused Gothamites pause. Worried that more buildings like it would result in a dark cave-like existance at street level the 1916 zoning resolution was passed. This law required that buildings of a certain height have set backs. Based on a mathmatical formula a building must either move back from the sidewalk (like the towers on 6th avenue around Rockerfeller Center) or have a retracement on the upper floors allowing for light and air to mingle with the buzzing masses below.
Ziggurat expained.
The Gotham Observer 