(Above) Marina City construction site, no earlier than March 1961. State Street at left. At upper right, the Dearborn Street Bridge is under construction. 80 caissons have been buried to support the east tower at upper left. The west tower will be built in the upper right corner. The platform being constructed next to the Chicago River will house commercial tenants.

“The towers will be like two trees,” explained Bertrand Goldberg in March 1961. “The central columns will house the elevators, stairways, and utility lines. They will be the trunks in the tree design.”

16 reinforced concrete beams will radiate 37 feet six inches from the trunk as branches. At the perimeter, columns will support the weight of the floor above. Beyond the floors will be the ten-foot-wide balconies, like leaves in Goldberg’s tree analogy.

“A person upon entering a Marina City apartment will be moving toward an expanding area and vista,” said Goldberg. “Leaving the elevator, the person finds the apartment door only a few steps away. From there, he will enter a small, triangularly shaped room. The apartment spreads out, and beyond the glass wall is the balcony and the horizon of downtown Chicago. It will be like living in the wide open spaces.” (Left) Floor plate for one-bedroom unit at Marina City.

Goldberg also described this as “kinetic space.” He maintained the circular design of the building helped the psychological well-being of its tenants. “In a box-like dwelling, an apartment dweller often gets a feeling of being merely an anonymous member of a large group.” The Marina City design, he said, tries to “capture the feeling of individuality that comes from living in a single-family residence.” Because the central column provides the major point of orientation, Goldberg pointed out “there are no long and winding corridors.” (Right) East tower floor plate, 21st through 52nd floors.

Appetite for concrete and glass

16,000 tons of concrete would be used to build the towers. Approximately 200,000 square feet of glass would be installed on the exterior of the 40 apartment floors of each tower, plus another 100,000 square feet of glass for the office building.

Concrete was supplied by a “ready-mix” plant, which means the concrete is pre-mixed and then delivered to the work site. After 28 days, the concrete had strength to withstand 7,000 pounds per square inch. A relatively lightweight concrete was used for beams (horizontal spans over an open space) and floors. Concrete of normal density was used for walls, (vertical) columns, and the main core. (Left) Work begins on the ground floor of the east tower.

Constructed over the inner of three concentric rings of caissons, concrete for the central core was being cast as a rate of eight feet six inches per day. The thickness of the core wall would decrease from 30 inches at the base to 12 inches at the top, 588 feet up.

James McHugh Construction Company was predicting completion of the residential towers by April 1962, with some apartments available a month or two before that. Charles Swibel, president of the property management company, was preparing to rent the apartments for $115 a month and up for an efficiency, $155 to $195 for a one-bedroom apartment, and $295 for a two-bedroom apartment.

A floor every 48 hours

Construction crews worked in a continuous 48-hour cycle. The same crews worked on both towers. The daily construction schedule appears to be...

6:00 a.m. – Construction sequence starts. Carpenters begin to strip the nine-foot-high wooden forms, external and internal, into which the concrete will be poured. The forms are divided into eight segments. Concrete arrives on a conveyer system at a maximum rate of 100 cubic yards per hour.

7:00 a.m. – A crane is raised and the external (outer) forms are reassembled, reinforcement bars are fixed into place, and openings in the core are boxed out.

Late morning – Half of a floor was finished and concreting starts on the second half.

12:00 p.m. – The internal (inner) forms are re-positioned. Surveyors set out for the next floor.

2:30 p.m. – Ready for concreting. Work begins on hoisting forms from three floors below, where they had been used four days earlier.

Late afternoon – Concreting is completed on the entire 12,000 square foot floor and carpenters are assembling the forms that will encase the concrete.

The work cycle continued until the following morning. Steel fixers positioned and secured the reinforcing bars used to strengthen the concrete. Then electricians installed electrical conduit. They were followed by plumbers and sheet metal workers. By 2:30 p.m., a third gang of steel fixers began the final work of assembling and fixing reinforcement for floor slabs.

By 6:00 a.m. the following morning, 48 hours after construction began on the previous floor, casting started on the next floor.

Special forms and mullions For the ramps and columns on the parking levels, concrete forms made of fiberglass were used for a better finish. On the 16-story office block, glass fiber molds were used to cast the arches of the lower stories. The textured finish was achieved by spraying colored marble chippings onto a rendering of sand and cement. To create the strong lines on the south face of the office building, special “seal forms” were used to cast the mullions that frame the windows and support 50 percent of the building’s floor load. (Left) Mullions, close up. By June 1961, the 32-foot-diameter central core for the east tower was taking shape. It rose about four stories from the foundation. One of the challenges Bertrand Goldberg Associates had to deal with was the effect Chicago winters had on the building. Exterior columns were partially exposed to the elements and connected to the building’s warmer core. As the building shrunk in the winter and expanded in the summer, this would cause the columns to grind against the floors.

In fact, when work was completed on about the 54th floor, workers started noticing small amounts of plaster residue from this grinding. The solution was to use a separation between the joints that was less dense and would allow for small movement. But they also had to trim many doors on the upper floors.

By the end of August, concrete had been poured for the 40th floor of the east tower core.

The construction schedule was accelerated, with one floor per day being completed by September 1961. The days were long, with crews working on the central cores from 4:30 a.m. to as late as 10:00 p.m. By having apartments ready by February 1962, developers could start renting them and paying off loans.

“The added costs from such an accelerated construction program,” said Charles Swibel, “will be offset by the effects of earlier occupancy and a reduction in interest paid on loans during the construction period.”

The goal was to have all of the apartments ready by September 1962.

Photographs by Portland Cement Associations. Illustrations by Marina City Online. A montage of PCA photographs...