In the run-up to Rio's Olympic Games, the Brazilian authorities violently evicted residents and bulldozed homes in the Olympic Park area. Writing in The American Conservative, Catherine Addington defends the informal favela communities that were removed, noting that it wasn't so long ago that Rio was attempting to integrate these self-built, self-governing communities into the city rather than aiming to eradicate them. That process was hardly flawless, but it's clearly preferable to the mass displacement happening now.
Aside from a somewhat forced comparison between the favelas and the New Urbanism, Addington's article is a good guide to the relevant history. Also worth a read: Priscila Néri points out that the talk you may have heard about a "disaster-free" Olympics sidesteps the disaster the games have been for the people who live nearby. And here's a golden oldie from the Reason files: Robert Nelson looks at life in the favelas and other informal Third World neighborhoods.