For the first time in human history, a majority of the earth's population lives in cities. But though great cities have been among humanity's supreme achievements down through the ages, they now face an uncertain future, threatened by forces that could undermine the very things that have made them great.
On November 8, 1519, Bernal Dfaz del Castillo saw a sight that would stay with him forever. Serving under Hernando Cortes, the 27-year-old Spanish soldier had already encountered… more