The Castillo de Chapultepec, Parque Niños Heroes, go explore around Reforma, see the Angel de Independencia, go visit the pyramids in Teotihuacan, it’s a history lesson and a half but they’re stunning, eat churros, get street tacos for a dollar, go to the Museo Nacional de Antropología. If your feeling speedy go to Artz Pedregal and go shopping to your hearts desire. Enjoy!