"Is that where -?" whispered Professor McGonagall.
"Yes," said Dumbledore. "He'll have that scar forever."
"Couldn't you do something about it, Dumbledore?"
"Even if I could, I wouldn't. Scars can come in handy. I have one myself above my left knee that is a perfect map of the London Underground."

Harry Potter and the Philosopher's Stone - Chapter 1 : The Boy Who Lived
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