MEXICO CITY (AP) — Mexico City, the most populous city in North America, is a vibrant, bustling metropolis that blends rich history with modern culture. Whether you are marveling at ancient ruins or enjoying contemporary art, there is a palpable energy in the air and it will be present during the World Cup this summer. With a metropolitan area of some 23.1 million people, traffic congestion is quite intense during rush hours, especially in the area near Azteca stadium. The city has pollution