The woman had been trapped in an 8- to 10-inch wide space between the exterior walls of the buildings since about 3:45 a.m. PST, The (Portland) Oregonian reported.
A fire department spokesman said he did not know how the woman slipped into the tiny space between the 20-foot walls that left her dangling 4 feet above the ground.
About 20 firefighters used industrial saws and jackhammers to cut a 2-foot square opening in the wall to free the woman, who was not identified.
Straps were placed around the woman during the rescue operation to prevent her from sliding farther down.
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