Very central place right next to Puerta de Sol. The apartment is great and I recommend it to anyone!
I stayed there for a month for a "workation" and had a couple problems with the internet which was a bit slow for work, and with the washing machine which took me a while to figure out (make sure you ask Alicia how to use it).
Alicia and her husband were extremely responsive, and incredibly helpful whenever I needed their help. Thanks again for everything!