Pahnu is the best cultural reason to come to Tecozautla. The site belonged to the Xajay culture, a less familiar Otomi-related tradition, and its hilltop setting gives the pyramids a strong sense of place.
The ruins are modest compared with Teotihuacan or Tula, but they are far quieter and more tactile. You can still climb the main pyramid, look across the dry hills, and understand why this was a ceremonial landscape rather than just a convenient settlement.