Bertha has a great apartment in a nice location close to Calle rio Reforma. She is very attentive and always asked every few days if I needed anything for my stay. The location is about a 5-10min walk to Calle rio Reforma and a 20min walk to the subway. The area is really nice, and in my two weeks of being in CDMX i did not fee unsafe at all. Best of all there is a cafe downstairs if you want coffee in a pinch or want to sit down for a nice breakfast.