Hostal Cruz Sol is a fantastic place
If you do a search, you'll see loads of comments on this site already.
I love it. I stayed there this summer in a triple room. My son stayed earlier in the year in a single room - he was only 15 at the time, and felt very safe and happy there. It's clean, convenient, efficiently run by helpful and pleasant staff .. overlooking a small plaza .. you can see Plaza Major from some of the rooms.
I can really recommend it.