Take the metro to Line 2's southernmost terminal, the station called Tasqueña. Exit through the turnstiles, and then follow the autobuses (buses) signs to the Southern Bus Station, about five minutes walking distance away. Most of your fellow metro passengers probably will be heading for the bus station, so just merge into the general flow across the elevated walkway, and then down the street lined with taco and tourist stands, and follow everyone else.
Inside the terminal the company providing most frequent service to Tepoztlán is Autos Pullman de Morelos, with departures leaving about every half hour. In 2003, Keith Baines reports that tickets cost 49 pesos, or about U.S. $5.00.
Once you are ticketed and stand on the departure platform, study the large electronic sign announcing departures. It lists bus numbers and identifies which bays the buses depart from. Bus numbers usually appear both on your ticket and next to the bus's door. Your seat number should also be designated on the ticket, next to the word asiento, which means "seat." Inside the bus, on the little plates mounted on the luggage racks designating seat numbers, the letters VENT stand for ventana, which means "window," and PAS stands for pasillo, which means "aisle." Thus VENT 9 means "Seat 9, next to the window."
The trip takes a little over an hour, and takes place amidst very striking mountain scenery. In Tepoztlán you are deposited at the tiny Autos Pullman de Morelos bus station shown at the right, from which you can hike downslope for about five minutes, to the downtown area and the tianguis. During your walk, notice the remarkable rock columns rising from forested slopes of the surrounding mountains, the Sierra de Ajusco. The mercado area announces itself when, on the right, crowds of people appear among merchandise mostly spread below brightly colored plastic tarpaulins.
After touring the various stands you might take a meal in the comedor area. I recommend the quesadillas containing squash flowers (quesadillas con flor de calabaza) or, even more interesting, quesadillas with the delicious parasitic fungus known as corn smut, or cuitlacoche. Ask for quesadillas con cuitlacoche.
Tepoztlán is home to the 16th-century Dominican convent shown at the left, rising majestically at the mercado's east side. If you visit the convent, be sure to notice the 300-year-old American fig tree at the entrance. Also, a hard climb following signs up the hill overlooking town will bring you to Tepozteco Pyramid, built by ancient Tlahuica Indians to honor Tepoztécatl, the god credited with originating pulque, the poor-man's alcoholic drink fermented from sap of the maguey plant.
To return to Mexico City, hike back to the little Autos Pullman de Morelos station and buy a ticket. It is possible that your bus will not come to the station for you, but rather a free shuttle will carry you to the service station atop the hill, where you will wait a few minutes for the bus. The bus will return you to Mexico City's Southern Bus Terminal, where you can follow the crowd back to Tasqueña Station.