Wind tunnel tests at Illinois Institute of Technology concluded this new shape was more efficient, at least more wind-resistant.

The idea of round buildings may have come from a rejected design, by another architect, for Executive House, a hotel completed in 1960 across Wacker Drive from Marina City.

It may have come from Chinese-American architect I.M. Pei, who in 1949 designed “The Helix” (left), a 22-story cylindrical apartment building for New York developer William Zeckendorf. Elevators and stairways inside the core were surrounded by a circular corridor, followed by a ring of bathrooms and kitchens, and then living quarters and balconies. The Helix was never built. A version of it was proposed in the mid-1950s for lower Manhattan but that was not built, either. Goldberg did design a cylindrical motel in 1957 that was not built. The idea may have endured and found its way into the design of Marina City two years later. Or the inspiration may have been a railroad car.

(Right) Cutaway drawing of the “Unicel Freight Refrigerator Car,” a diesel-powered boxcar with rounded corners, designed by Bertrand Goldberg for Pressed Steel Car Company.

In the early 1950s, John Snyder, president of Pressed Steel Car Company, asked Goldberg to design a new freight car built of laminated plywood, replacing steel that was still in short supply after World War II.

Goldberg created a tube-shaped structure made of layers of strong plywood. The plywood was then laminated under heat with special plastics. The Unicel Prefab Freight Car was unveiled in 1952 with much fanfare at Merchandise Mart in Chicago and The Waldorf-Astoria hotel in New York.

“I believe the boxcar done in the early 1950s was for my father the real structural breakthrough,” said Geoffrey Goldberg in 2008. “It is a tube structure. And put that together with the use of curved concrete in a later project – work in the mid-50s for a sewage plant in Nashville – and it’s not too far to get to a vertical tube, the concrete core, at the heart of the towers at Marina City.”

Although the plywood freight car was lighter and less expensive than steel, pressure from the steel industry kept it from catching on.

On November 3, 1959, Goldberg signed an agreement to design for Marina City Building Corporation “two commercial buildings, an auditorium, and two apartment buildings containing approximately 1100 dwelling units; said structures to be erected at the corner of State Street and the Chicago River, Chicago.” Bertrand Goldberg Associates would be paid 2.5 percent of the construction cost, plus 0.8 percent to supervise the project, 1.0 percent to negotiate with the Federal Housing Administration, and 2.5 percent to design the commercial portions of Marina City. Assuming a construction cost of $36 million, the total of these fees would amount to $2,448,000 – or the equivalent of $19.9 million in 2014. (Left) An agreement signed by Bertrand Goldberg to be the architect of Marina City.