For a long time, Rio deserved its reputation as a city to watch yourself in; violent street crime was rampant, and there were regular police raids in the favelas. Eight years ago, when I traveled there alone, I was more or less forbidden to venture anywhere by myself except the well-to-do neighborhoods of Ipanema and Leblon—and that was during the day. (Walking around at night? No way.) Today, in the wake of the World Cup and reforms under President Dilma Rousseff, Rio is transformed. There are now tours of favelas (don't miss the miniature city of Project Morrinho in the Pereira da Silva favela). As in any big city, you need to exercise good judgement. But put it this way: I took a bus back to my hotel at 9 p.m. last March, and felt perfectly safe.