I spent the day looking at the site and the museums, and wandering through the streets of old Mexico. To start with Tenochtitlan, here are pictures of a model of the ceremonial center, and the layered structure of the main temple.
a couple of pictures of the site
and of some of the sculptures housed in the museum (the second one is one of the many representations of Tlaloc, the God of Rain and one of the most important gods of the Mesoamerican pantheon).
One of the most important pieces in the museum, here restored to its original colors, is the monolith that represents the dismembered body of Coyolxauhqui. According to Mexica mythology, this goddess conspired with her 100 brothers against their mother, when she found that she was pregnant. The newborn was Huitzilopochtli, the God of War, who came out of the womb fully grown as a warrior. He killed his 100 brothers, dismembered his treacherous sister, and became the main god of the Mexicas. (The third important god was Quetzalcoatl, the Feathered Serpent).
At the end of the 16th century Alexander Von Humboldt visited Mexico City, and enthusiastically dubbed it la Ciudad de los Palacios for its magnificent architecture.
My Mom was worried about my safety while visiting the city, which admittedly is not very safe, but all I found were families having a nice day out in the central park (la Alameda), visiting the Museum of Popular Arts, and overall having a great old time :)