Museo Fuego Nuevo explains the New Fire ceremony once held on Cerro de la Estrella, where Mesoamerican communities marked the end of a 52-year cycle and the start of another. The museum gives useful context to the hill's archaeological remains, including finds that point to ceremonial use long before the Mexica period.
It is a good stop if you are making the trip out to Iztapalapa for the national park. The displays turn what might otherwise feel like a simple viewpoint into a place with a much older ritual landscape behind it.