In 1955 he joined the San Francisco office of Skidmore, Owings and Merrill as chief structural engineer, and in 1958 moved to SOM Chicago as an architect. Beginning in 1961 and for the next 35 years he also served as professor in the IIT graduate program. He was elected an SOM general partner in 1966 and officially retired in 1979, but continued to work with the firm until 1983.

Goldsmith is recognized as the most important expositor and practitioner of Mies's concept that architecture "comes out of construction" and ought to be chiefly an expression of structure. Goldsmith first understood and embraced this principle while working as project architect and structural engineer on Mies's celebrated Farnsworth House (1951). In his IIT graduate thesis (1953), nominally done under Mies but independently, Goldsmith was the first to propose and give examples of practical exoskeletal systems to address the significant lateral forces experienced in very tall buildings (those above about 40 stories). He refined his ideas in a 20-year collaboration (at IIT and SOM) with the celebrated structural engineer Fazlur Khan. The first exoskeletal towers were realized by SOM in the early 1960's, with Goldsmith and Khan as theorists and designers. This interplay between academic research and architectural practice had a world-wide impact on the development of tall and long-span structures.

As an SOM designer and partner during this ground-breaking period, Goldsmith and his colleagues further extended his theorizing in spectacular buildings and projects, many now officially landmarked. His best-known work includes the Kitt-Peak Solar Telescope (1962), the Oakland-Alameda County Coliseum and Arena (1966), the Republic Newspaper Plant (1971), and the unprecedented (though unbuilt) Ruck-a-Chucky cable-stayed bridge (1978). Goldsmith also designed several SOM buildings for the IIT campus, including the Gymnasium and major classrooms and labs. After retirement from SOM he continued to collaborate and consult on major bridge designs with several of the world's leading structural engineers.

In his parallel career as IIT Professor of Architecture and graduate Thesis Advisor, Goldsmith greatly expanded an advanced degree program first conceived by Mies. In a remarkable joint academic career with his student Prof. David C. Sharpe, the two directed 280 thesis projects between 1961 and Sharpe's retirement in 2009. This work —always a fully-developed building or structure embodying and often testing the bounds of "structural architecture"—constitutes another of Goldsmith's legacies: architectural ideas meticulously developed in collaboration with students who went out into the world and, as Goldsmith directed, did "good work."

Goldsmith, often described as a "poet of structure," is best remembered for the structural architecture that he conceived and practiced—the critic Alan Temko aptly called it "structural humanism"—which Goldsmith precisely defined as "a complex realm of the building art in which architecture, engineering, and aesthetics interact to make structure the central expressive element of design." It followed, he argued, that a building "should be built with economy, efficiency, discipline, and order." His built works and unbuilt masterpieces display his conviction that "a building should be a coherent work of structural art in which the detail suggests the whole and the whole the detail."

-Edward Windhorst