Tonantzintla
You must visit the chapel. Also the church in the town of Acatepec, within walking distance, is worth seeing.
Cholula:
Renowned to have 365 chapels, aereal photography show "only" about 60. Many are worth a look. Visit also the Zocalo (central square).
The most voluminous pyramid in the world is here (if in doubt consult the Guinness book of records).
Puebla:
What you must not miss: