Hi. Yeah, I've heard that "sinking" thing before. It's not the weight of the city, as some believe - it is that the city was built on a lake. If you have an interest in history, check out Michener's
Mexico (maybe Gary Jenings'
Aztec, as well) and it will explain much. Anyway, my house is on rock.
This is a view from where we sometimes take comida. Not
quite Mexico but Sante Fe. If you know Mexico at all, you'll know that there are many municipalities and colonies forming the greater Mexico City area.

If you look closely, below the most interesting building, you'll see a pasero, or micro-bus (we just call 'em "micros"). These little buggers are the bane of D.F., or Mexico City. They puke whatever it is the nastiest diesels puke and are responsible for a vast majority of the pollution - They are government run.
This shot shows some of the diversity strangers don't think of when they think "Mexico City". It's just on the other side of the defining highway mentioned below.

It is from right off the Periferico, the road that circles the city, and is from the parking lot of a Swiss restaurant showing some more modern buildings.
This

While not technically
In D.F., is just on the other side of that hill in the background of the first picture. We take the kids to ride horses at a club here. I hope you notice, that while the lower parts of town have horrendous smog at times, I almost never see it because I prefer the start of the rainy season there and when it's cold and smoggy we are usually in Cuernavaca.
Hope this opens your eyes a bit about a wonderful city with an official population of about 27 million - depending on who's taking the poll! More restaurants, more culture, more museums, more people, and
almost more fountains than any place else in the world. Insurgentes is the longest avenue in the world. On some days you can pick between horse races, opera, any number of entertainers, Formula 1, symphony, have any food you want, then do antros until tamales at sunrise.
Talked to my wife a bit ago, it snowed there today. We don't lock the cars in our neighborhood and the house doesn't even have locks..to dispel another myth.