Inner Workings of the World's Megacities

Erik Meza for TIME

Law and Disorder

After a decade of rampant crime, officials and citizens of Mexico City are trying to fight back

Winning the 2012 Olympics gives London cover to spend billions to keep the city competitive
• Photo Gallery

In Bangkok, every hour is rush hour. What it will take to unravel the city's epic traffic jams
• Photo Gallery

India's biggest city has to move its productive poor, carefully, to build needed infrastructure
• Photo Gallery

China's capital has made progress against pollution, but its Olympian effort still might leave some gasping
• Photo Gallery

Most of the world's population now lives in cities. TIME looks at the prospects and problems facing the globe's largest urban centers.