The Valley’s not a valley
The Valley of Mexico, where Mexico City is located, is not actually a valley at all, but a plateau that millenia of erupting volcanos and earthquakes created mountains around. That’s why there is no natural drainage in Mexico City and the reason why massive yearly flooding occured until the Aztecs built a system of dikes to control the flow of water into the “valley.”
Why it shimmies and shakes
Mexico City sits right on what is known as the Pacific Ring of Fire, a zone of fault lines that runs along the Pacific tectonic plate and some smaller plates in the Philippine Sea and Pacific Ocean. It also sits atop of tectonic plates that continue to shift and move underneath each other. That means that the city is located in the one of the most siesmically active areas on the globe.
The greener side
Despite its reputation for being super polluted, Mexico City is one of the greenest megacities in Latin America. Part of this distinction has to do with the fact that the Desierto de los Leones, a nearby natural reserve, is included within the city limits as well as the Parque de Chapultepec, which is almost double the size of Central Park.