For Rebecca Summer, a PhD candidate in geography at the University of Wisconsin at Madison who has studied alleys in the District, how alleys are regarded in the public’s mind offers a clear snapshot of the city. Where alleys used to be treated as breeding grounds for vice, they are now celebrated as edgy and quintessentially urban, she said.“Now, they’re still hidden,” Summer said. “But instead of people denigrating them, they’re seen as cool spaces.”