First things first. Prentice Women's Hospital was not granted landmark status last night, clearing the way for Northwestern the demolish the Streeterville structure and build a new research facility. Now, here's what happened.

For a quick rundown on the history of Prentice, check out our timeline, but the quick and dirty is Northwestern, which owns the Prentice building, wants to tear it down and build a new research facility, while preservationists argue that the site should be named a landmark and protected by the city.

To qualify for a landmark, a building in Chicago must meet two of seven criteria. Prentice actually meets four criteria, according to the commission (page 25): it was a part of Chicago heritage; it had exemplary architecture, which Whet Moser has covered; it was the work of an important architect, Bertrand Goldberg (also known for the Marina City complex); and it had a unique visual feature (that clover shape!).

The Chicago Commission on Landmarks met yesterday to finally vote on whether to grant Prentice landmark status, which could have saved the building from destruction. Around 4:00, the board voted unanimously to grant a preliminary landmark designation, calling it a "boldly sculptural building."

After a preliminary landmark designation is granted, according to the commission, the Department of Housing and Economic Development must submit a report on how the landmark designation would affect the surrounding area. In the past, the report has taken time to complete (usually it is presented at the following board meeting), but in this instance, the commission had the report on Tuesday, according to the Chicago Tribune.

Citing the report (scroll toward the end of the document), the commission voted at 6:45 p.m. to revoke landmark status to Prentice, saying Northwestern's needs and the economic report findings outweighed the benefits of preserving the building. Only Commissioner Christopher Reed voted to protect the landmark.

Now, as to why the double vote within two hours. "What happened was a condensed version of a process that sometimes takes a month," says Rafael Leon, the chairman of the landmarks commission. "In this case, [the Department of Housing and Economic Development] was ready for it. This has been in the public eye for 18 months."

The Save Prentice coalition and Landmarks Illinois disagree, saying the original vote was only symbolic.

"It's so overwhelming that this building qualifies [for landmark status] that if they were to vote no, it would look like a farce," says Lisa DiChiera, the Director of Advocacy at Landmarks Illinois. "So basically the way they set up the agenda was giving them the opportunity to vote 'Yes, we acknowledge that this building meets all the necessary criteria for Chicago landmark designation.' Then the next action item, [the report], which they had already seen, was officially presented to the public, asking for the commission to rescind that decision."

Leon counters that meeting criteria is not enough.

"I think people need to understand—even if a building meets seven points of the criteria, that doesn't mean it has to be designated a landmark," he says. "The ordinance gives the Department of Housing and Economic Development some flexibility in considering some other planning factors…in making a final recommendation. I understand why people feel angry about it, but I feel that people also think just because a building meets the criteria, it's automatically designated a landmark. That's not the case."

In the meantime, Northwestern is preparing for a design competition in 2013 for the new research facility.

Photograph: Chicago Tribune