Beijing, with 21 million people, has some of the worst air pollution and traffic congestion in the world. Residents agree that something must be done, but don't ask them to get rid of their beloved cars.
Twenty-five years ago, at the height of the Cold War, a Soviet court sentenced 19-year-old West German Mathias Rust to four years in prison. He flew a single engine plane into Moscow and taxied into Red Square.
Nearly 9 million people call Mexico City home, and some 21 million people live in the metro area. It can take hours to get around, especially during rush hour. One solution that’s catching on though: Riding a bicycle.