The tall office building
Sullivan’s tripartite skyscraper (1896): base, a shaft of identical floors, and an attic capital, with the steel frame revealed in a cutaway.
The rules it illustrates
The skeleton carries; the wall only encloses. In a framed building the columns and beams carry every load; the outer wall can be reduced to a light cladding hung on the frame, floor by floor, and need grow no thicker as the building rises.
The tall building has three parts. Treat a tall office building as base, shaft and top: an open, accessible ground storey for shops and entrances; an indefinite stack of identical office floors expressed as one; and a distinct attic that closes the composition.
Form follows function. The outward form of a building should arise from, and express, what the building does and how it is made, as the form of every living thing expresses its life.
Where it appears in the book
In the styles Chicago School, Art Deco.
In the chapters Frame and Skin, The Modern Movement.