The Commission on Chicago Landmarks placed the Marina City towers on the path toward preservation Thursday. View Full Caption DNAinfo/Ted Cox

CITY HALL — The Marina City twin towers moved a step closer Thursday to being declared official Chicago landmarks.

The Commission on Chicago Landmarks formally placed the towers on that path by granting them preliminary landmark status at its meeting Thursday at City Hall. It was one of the first steps in a formal landmark process that will include studies and hearings ahead of what's expected to be final passage by the City Council.

The city's Department of Planning and Development recommended the move in a 52-page report calling Marina City "an icon of Chicago architecture and urban planning."

The city's architectural historian Matt Crawford presented the department's report, testifying that Marina City was "designed as a complete city within the city," with its residential towers rising above car garages, as well as a theater (now the House of Blues), bowling alley, shops, restaurants, office building (now a hotel) and with its namesake marina below at the level of the Chicago River.

Bonnie McDonald, president of Landmarks Illinois, pointed out that the Marina City towers are "affectionately known ... as the corncobs." View Full Caption DNAinfo/Ted Cox

Crawford called it the "signature" work of architect Bertrand Goldberg, declaring Marina City "the defining project of his career."

Crawford said Goldberg's "expressionistic" style, using organic shapes in this case reminiscent of corncobs, was in marked contrast with the prevailing International Style of Mies van der Rohe at the time. He said Marina City was intended to act as a Downtown anchor for city residents, under a revitalization campaign launched by Mayor Richard J. Daley in an era when many Chicagoans were fleeing to the suburbs.

According to Crawford, Downtown Ald. Brendan Reilly (42nd) "requested and supports" landmark status for Marina City.

Bonnie McDonald, president of Landmarks Illinois, said Marina City had her group's "full support" as a landmark, adding that the towers were "known affectionately ... as the corncobs." Preservation Chicago likewise supported the measure.

Earlier this week, Chicago architecture buffs cheered recognition of the Marina City complex as Goldberg's masterpiece. His use of concrete in the skyscrapers was innovative, as the floors were basically poured in "petal" shapes, as seen from above, stacked atop each other like records on an old-style turntable.

Video has resurfaced of the Marina City towers being constructed in the early and mid-'60s — not coincidentally produced by the Portland Cement Association.

The department's Eleanor Gorski said the process would next lead to a public hearing and a more detailed study, followed by a request for consent from the various owners of the complex's five buildings. More public hearings should follow, before final approval (or not) from the commission and the full City Council, with landmark status expected to be granted early next year.

Landmark status works to formally preserve a building, and can lead to tax breaks for the owners in maintaining the property in a respectful manner.

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