Five years ago a seal broke in a third-floor window of the Milton hospital near Boston. A chemical deposit trapped in the window pane started to turn the glass a blotchy white. Last week the blotches came together in the shape of the Virgin Mary and have now become a religious shrine to which more than 25,000 people have flocked.

Dozens of bouquets have been placed beneath the window. A hospital worker saw a mother help her son, who uses a wheelchair, touch the wall with his legs.

"It seems like every day it gets clearer," said Sharon McGarty, an administrator in a doctor's office. "It used to look like just a dirty window."