Standing at La Plaza de Las Tres Culturas—an evolutionary intersection where Aztec ruins sit alongside a 17th-century church and 21st-century modernity—what you’ll first notice is that the church and the plaza are leaning. And that is because Mexico City is sinking. Yup, the entire city, in fact, is one big swamp, built in this location because here was spotted an eagle with a serpent in its talons, perched on a cactus—a prophetic sign for the Aztecs to build a city after wandering nomadically for several centuries.

For modern-day Mexico, that means that all over the city, there are leaning, sinking buildings as well as ruins that are retreating into the earth.

Aztec ruins in the foreground with La Basilica (the old one) leaning in background 
​By Deror_avi - Own work, CC BY-SA 3.0

La Basilica de Guadalupe, a modern structure (hideously out of architectural sync with the adjacent churches) that holds 10,000 parishioners, faces a plaza where you can also see the old Basilica (sinking), La Colegiata (sinking), and high on the hill behind, El Templo de Cerrito.

The story behind La Virgen de Guadalupe, which has produced a kind of cult following in Mexico, as well as becoming central to Catholicism in this part of the world, goes something like this:

In 1531 an Indian named Juan Diego was walking over the hill on his way home from church (the Indians walked for miles to attend services in the city) when the Virgin Mary appeared to him. Over a short period of time, she appeared to him several more times, each time telling him to send a message to the bishop to build a church on a nearby spot.

When the Indian approached the bishop, he wouldn't believe that the message actually came from the Virgin) and he asked for proof. When the Virgin appeared to Juan Diego again, he told her that no one believed him because he was an Indian, and they wanted proof. She gave him a bundle of red roses and told him to fold them in his jacket, take them back to the bishop, not showing anyone until he got there.

When he returned to the bishop he opened his jacket and the roses fell out. Imprinted on his frock was a perfect image of the Virgin. The bishop believed, and had the church built (the old Basilica).

The faithful make the pilgrimage to La Basilica de Guadalupe 
​By Karolja - Own work, CC BY-SA 4.0

​The entire square is considered a holy place, a mecca for millions of people who make the pilgrimage to visit the site. Even poor people come from the outer regions of Mexico and camp out in tents on the plaza for several days. On the periphery are hundreds of vendors selling rosaries and images of the Virgin. The most pious crawl on their knees across the plaza, approaching the Basilica in prayer position.

While church services are going on, visitors can enter a passage behind the church altar and shuffle by the huge 24K gold framed frock of the young Indian and you can clearly see the colorful image of the Virgin peacefully looking down. The guides joke that instead of being called "catolicos," Mexicans are often called "Guadalupanos"—for such fervor around La Virgen de Guadalupe.
 
Regardless of your religious leanings, it’s well worth seeing the churches and holy spots of Mexico City—before they sink into the earth.

Soon after you’ve had your first cup of rich dark hot chocolate in the city of Oaxaca (wa-ha-ka), you’ll be making plans for Mitla, one of the most important archaeological sites in Oaxaca (the name of the state/region, as well as the city).
 
Built around 800 BC by the Zapotecs (and the Mixtecs), an Indian race that followed the Mayans, the ruins of Mitla have remained remarkably well-preserved. The huge complex is laid out around a central, cross-like structure, with each facade of the "cross" featuring nine panels of mosaics--elaborate stone puzzle pieces perfectly fitted to one another.

Zapotec innovation in pre-Colombian times
When the Spaniards arrived in 1521, they assumed that because of the cross-shape of the structure, and the small cross-like designs in the mosaics, that earlier Europeans must’ve arrived before them and influenced the Zapotecs with Christianity. But of course there was no relation, as there had been no earlier arrivals, and the four directions of the cross have been seen universally in many cultures to represent the four sacred elements—fire, air, water, and wind—as well as the four directions.

Within the site’s walls and tunnels, the same wondrous feat of geometric patterns gracing the walls of a large, dark passageway (complete with a creepy little bat flying around), in which the symmetric patterns on one side directly correspond to the patterns opposite, as if you were holding up a mirror—an amazing feat of geometry and mathematics that took modern scientists and graphic designers eight months to duplicate with a computer.

Further excavations have revealed cylindrical quartz bars, perfectly rounded and carved, and inside: phosphorus. Do you know what that makes? LIGHT. Nearly 3000-year-old light bulbs, developed by ancient Mesoamericans!

Mitla is also unique because it’s one of the sites not overtaken and altered by the Aztecs. As such it is a unique monument to the ingenuity of the Zapotec and their harmonious successors, the Mixtecs. Mitla was never buried under earth or ash, which means you can still see signs of the original colors painted on some of the walls, preserved for years because of a combination of calcium and lemon/lime juices. 

Mitla--every bit as memorable as that cup of dark hot chocolate you'll be sipping in nearby Oaxaca City.