Tepotzlán is the perfect day trip from Mexico City. A strange and wonderful mixture of colonial heritage and architecture, new age spirituality, and peaceful mountain vistas, this town certainly deserves its UNESCO designation as one of Mexico's "pueblos mágicos."
According to legend, this town sits on the birthplace of the Aztec serpent god Quetzacóatl, and its impressive pyramid ("Pirámide de Tepozteco," built in honor of Tepoztécatl, the Aztec god of the harvest) is now a gathering place not only for pre-Colombian enthusiasts, but seekers of all kinds who believe it to be a generator of groovy vibes. The pyramid is located at the top of of a cliff above the town and the 2km hike is recommended only for the physically fit. If you do go, start out early before it gets too hot and bring plenty of water.
Tepotzlán also offers plenty of more down-to-earth attractions, like a beautifully preserved historic center, a selection of nice restaurants and hotels, a bustling crafts market, an interesting monastery and museum, and a world renowned cooking school (lavillabonita.com). For breathtaking views of the valley and cliffs, have a meal at La Sibarita, which is perched on a hill high above town.