La Gruta has been serving Mexican food inside a natural volcanic cave on the eastern edge of the Teotihuacan zone since 1906. The setting is genuinely remarkable: a large vaulted limestone cavern lit by candles and shaded electric chandeliers, with rough rock walls and a sunken floor of polished volcanic stone. It is firmly on the tour-bus circuit but the food is good and the cave is the cave.
The menu runs to traditional pre-Hispanic-inspired plates: chinicuiles (maguey worms) for the brave, mixiotes wrapped in maguey leaves, pulque and mezcal cocktails. Reservations are sensible at lunchtime when the tour groups arrive. The walk to it from the Pyramid of the Sun gates takes about ten minutes.