FOOTPRINT MEXICO HANDBOOK Flying into Mexico City, the largest city in the world, you can't fail to be impressed by the scale of things. The city is filled with monumental architecture and sculptures and brightened by dramatic murals explaining the country's dramatic past. Beside the massive main plaza, the Zócalo, and the leaning cathedral that threatens to collapse on top of it, are the remains of the Templo Mayor, the pyramid at the heart of Tenochtitlán, the Aztec capital. Congested, polluted and gloriously manic, the Federal District is today one of the world's great cities, a living nightmare and definitely worth a visit.