My wife and I toured Mexico fairly extensively in 1964.
We even drove up the Nevado de Toluca (15,000 foot volcano) in a 1960 Pontiac on a semi-road which at a minimum required a four wheel drive and lots of road clearance, which the Pontiac didn't have.
But Mexico City D.F. was our undoing. We both got Montezuma's Revenge squared or cubed. And we were doing our best not to drink the water.
Before succumbing to Mr Montezuma's Revenge, we rented a guide and toured the city. At that time, the older part of the National Cathedral was sinking fairly drastically at one end. The newer part was still mostly level.
Out where the Aztecs built their city and pyramids, there was no apparent settling at all, so they evidently didn't build in the middle of a lake.
As I recall, in '64 the population was about 7.5 million, and the traffic was horrible. One drove in the City with one's eyes closed, just as the resident population did.
I've been touring Mexico each Sept. for the last four years (for a week). 15-25 guys from our church drive down to Chapultapec (an hour and a half south of San Diego) and build a house or two for Christian working families who:
1. are living in a car, cardboard and pallet shack, under a camper shell, tarp,etc.
2. usually have anywhere from 3 to 8 kids (or extended family with them)
3. Are married. 4. Work full time for $5.00/day
It's easy to see why millions come here every year:
Mexico is a hell hole. Five minutes after crossing the border (southbound) you enter another world, the stink, the trash, the dirt, the lousy infrastructure, the poverty, etc. it's pitiful.
The people we build the houses for, however, are friendly and generous. One family made us lunch every day while we built their house. We found out she borrowed money from a friend just to buy food and soda for us, and the food was very good. (We did pray harder before those meals!) One trick we learned was to take papaya enzymes before and after meals to kill the bugs and for the most part it works, the last couple years we've only had one or two guys go down.
Just doing our part to slow down illigal immigration, one family at a time.