For the past two weeks, a construction crew has scaled the limestone-and-granite skin of the Star Tribune headquarters in downtown Minneapolis trying to figure out how to remove six architectural medallions that were attached to the 95-year-old building in 1947.

Each 900-pound medallion represents an industry that was dominant in mid-20th century Minnesota: dairy, milling, mining, fishing, farming and lumber.

On Tuesday, the first medallion brandishing a mighty fish came down. A second depicting the state's wheat and corn bounty was removed Thursday. The others will soon follow.

"I've never done anything quite like this, although I've done a lot of work with concrete," said Darin Henson, superintendent of the Ryan Cos. crew removing them. "These are priceless. You can't replace them. You have to spend a lot of time to see the project through. So far, it's gone very well."

The city required that each medallion be preserved before the building, at 425 Portland Av., is demolished to make way for a public park. It's unclear at this point where the medallions will go.

The public green space is part of an office-residential project being developed by Ryan on five city blocks, including the one where the Star Trib­une headquarters is located, on the east side of downtown near where the new Vikings stadium is being built.

The medallions were sculpted by the late University of Minnesota art Prof. Ivan Dossef and affixed to the building during a renovation and expansion project that gave the building an architectural facade now known as Art Moderne. Preservationists argued before the City Council that the building should be preserved, but a compromise was reached that involved keeping elements of the facade. Preservation Design Works of Minneapolis was hired to document the building's history.

Detaching the medallions after more than six decades has proved to be no small task, Henson said. Each medallion measures 52 inches in diameter, and is encased in limestone.

To get at them, workers removed the limestone facade, then chipped away at concrete behind them. Once their anchors were exposed, they were lifted from their moorings and carefully lowered to the ground by a series of pulleys.

The medallions will be stored at a Ryan facility in Fridley until their fate is determined.

After decades in which the medallions could only be seen from a street-level vantage point, Henson and his crew are the first to see them up close. "They're very beautiful," he said.