From August 7 to 31, Edinburgh turns into the busiest stage on earth as the Festival Fringe returns, filling hundreds of venues across the Scottish capital with thousands of performances. Open to anyone who can find a room to play in, it draws theater-makers, comedians, musicians, and dancers from around the world, unknowns and household names alike, and much of it is free. No event matches its scale or unpredictability, which is exactly why it remains the world’s great proving ground for live performance.