The city of Chicago plans to tear down a historic building at the old Michael Reese Hospital — despite promises to save it.

The main hospital building is more than 100 years old. Landmarks Illinois says the building’s one of the few examples of a prairie-style high-rise. It was also the site of many medical innovations.

The city bought the hospital campus in the summer of 2009, planning to build the Olympic Village there. The city didn’t win the Summer Games, but demolished most of the other buildings anyway, including several that famed architect Walter Gropius had a hand in designing. The city vowed to keep the main Reese building and later also said it would try to preserve one of the Gropius structures.

Now Mayor Richard Daley says the main building is deteriorating and unsafe. Officials say the building was in poor shape when the city bought it, and now the roof’s starting to cave in.

Daley says it will cost too much to stabilize, especially during hard economic times.

Jim Peters, who heads Landmarks Illinois, says that’s a tremendous disappointment.

“It is the one building down at Michael Reese that even the city agreed to preserve up front when the Olympics were being discussed,” Peters says. “And as we all know, they ended up tearing down virtually everything else, and now they’re going to tear this down.”

“So I guess we’re better at demolition than preservation,” Peters said. He’s worried now about what will happen to the last Gropius building.

Peters questioned how the main building could fall apart in such a short time. He says there are plenty of properly-secured vacant buildings in fine shape a dozen years later.

Preservationists have charged that the city didn’t do enough to secure the site. They also said the city allowed salvage crews to remove items they shouldn’t have and to damage the property by breaking windows and throwing furniture out through those windows.

The city says despite its “best efforts,” squatters are still occupying the building and stripping the property for salvage. A spokeswoman for the Public Building Commission says those efforts include increasing security. She did not have details about when the security was added or what that entailed, but said she’d have that information by tomorrow.