I agree with Navigator except for "Mexico is a desert"
My aunt lived in Mexico City and I spent a summer in the 50's with her and I for one loved the city and its history.
Mexico city was built on a lake, soil is still soft, buildings still sink or shift there.
Mexico City is situated in the tropical zone and lies at an altitude of 7,240 feet (2,230 m) above sea level. This high altitude largely determines the climate of Mexico City. The city experiences hot summers and mild winters with an annual average temperature of 64°F (18°C). It has very small seasonal changes. January is the coldest month and May is the warmest month while rainfall occurs mainly between June and October.