I visited this site during my trip to Mexico in 2009 and found it fascinating: Just the largest pyramid in the world is an impressiv fact. But it is hidden under a large hill, crowned with a important pilgrimage church, supposedly destroyed several times by lightning as vengeance of the old, previously revered god. It is somehow a mystery to me why not more of the pyramid is excavated since it could be as important as Teotihuacan. The view at the hill with the Popocatepetl in the background is priceless even on pictures. I am curious it this site will ever make it back on the tentativ list on its own or as an extension of Teotihuacan?