Berlin, Germany was once divided in half by a wall, built to keep people separated after WWII. But since the wall fell, the city has transformed into a bustling, creative, open, and diverse global metropolis.
More than half the world's population resides in cities. Kari Byron visits New York City to work with urban planners and innovators striving to make the city more livable.
By 2050 the world's population is on track to grow by more than 35 percent. Kari travels to Detroit and San Francisco to find out: how do we better feed our growing planet?
