Mexico City is floating on a lake bed a mile and a half high. Nowhere is Mexico's explosive past better depicted than at its central plaza, the Zócalo. Surrounded by some of the finest buildings of the Spanish colonial era, lie the remains of one of the Aztecs' principal monuments, the Templo Mayor. The temple's mysterious shapes, unusual icons and enduring colors stand as a haunting tribute to the pre-Hispanic civilisation that flourished here long ago.

Also called the Distrito Federal (Federal District) or simply D.F., Mexico City is the country's capital and center of commerce, finance and the arts. It ranks as the world's second-largest city, after Tokyo, with about 20-25 million inhabitants in the metropolitan area.

To the west lie the poshest residential areas, beyond Chapultepec Park, in a zone called Las Lomas (The Heights); and to the south, in San Angel and Coyoacan, once independent towns and still delightfully colonial in style, and in Pedregal, near the national university, where the modern homes are more reminiscent of the US suburbs. Other interesting neighborhoods, or colonias, are Condesa, Mexico City's answer to SoHo, and Roma.

To the north are big factories. Many lie across the city limits, in the State of Mexico, in an area best described as a hybrid of First World industrialisation and Third World poverty