A Cook County Judge on Thursday granted temporary landmark status to Prentice Women's Hospital.
Judge Noel Cohen's ruling means the city cannot issue a demolition permit.
The owner of the Bertrand Goldberg-designed building, Northwestern University, wants to bring the structure down so a new medical research facility can be erected in its place.
It's a move supported by Mayor Rahm Emanuel.
But preservationists allege in a lawsuit that the Chicago Landmarks Commission violated a city ordinance last month when it rescinded the building's landmark status in the same meeting it was granted.
"We're going to do no harm to Prentice while this can be resolved," Cohen said, according to the Chicago Sun-Times.
The building, 333 E. Superior Street, has been vacant since 2011.