Rambla 31b is an extremely good, central location, close to the Passeig de Gracia station and other key metro Barcelona hubs. Shopping of all kinds is nearby, including the wonderful bakery right under the bedroom windows which awakens you with the fragrance of freshly baked bread every morning -- or it would, if you could leave the windows open. Owing to the central location, the traffic and other noise is pretty intense all day and most of the the night -- especially weekend nights.
The apartment is managed by a rental agency and they are pretty responsive if you can telephone them.