Marcia's flat is a great place to stay. It is very comfortable and clean and feels safe with a 24 hour guard. It has everything that you need for a stay in Mexico City. It is in a great location close to a lively shopping area. It is within easy walking access to tourist attractions such as Belles Artes, Zocalo, restaurants, cafes and parks. It is also close to metro stations to go further afield eg Frida Kahlo's house. Marcia has left lots of good information about what to do and where to go.
Marcia is a great host and responded immediately to a couple of requests. I would recommend this as a place to stay in the centre of Mexico city.