The Wainwright Building in St. Louis is the work of the architect Louis Sullivan, and it is an attempt to give the steel-frame skyscraper not just a structure but a language of form. If the Home Insurance Building made the steel frame possible, the Wainwright asks how that frame should look.

Sullivan's problem was new: the steel frame, stacking floor on floor, produced a very tall but formally "indeterminate" mass. Sullivan divided the ten-storey building into three parts like a classical column: the wide-bayed base at the ground (the pedestal), the repeating office floors in the middle (the shaft), and the ornamented cornice floor at the top (the capital). The real gesture is in the shaft: Sullivan placed more vertical piers on the facade than the actual number of steel columns (which in reality break at every floor), making the building look more vertical, a mass flowing upward. The horizontal floor slabs are recessed and left in shadow; the verticals are brought forward.

This is the architectural counterpart of Sullivan's famous principle — "form ever follows function": the building's function (a vertically rising stack of offices) is expressed directly in its outer form. The Wainwright Building thus carries the steel-frame skyscraper from an engineering problem into a mode of architectural expression; it begins the aesthetic language of the modern tall building.