The Sierra de Guadalupe is a chain of mountains in the very north of Mexico City. It marks a natural limit between the densely populated communities of the City and those in the surrounding areas of Mexico City.
Today, especially with the opening of the Cablebús Line 1 in 2021, the northernmost reaches are open and accessible to international visitors. The south of the Sierra extends well into the City. The Tepeyac Cemetary marks the historically significant site of the Marian Apparitions. These led later to the establishment of the Basilica of Our Lady of Guadalupe. And the Basilica later lent its name to the entire chain of mountains.
Depending on who's counting, and how, the chain can be said to have consist of some 22 different peaks. Among these, the Cerro de Tepeyac is actually the smallest. The Pico Tres Padres is usually cited as the highest, at 3,000 meters. It's immediately across the northernmost point of Mexico City, and geographically in Mexico State.