Airbnb in central Barcelona

You might want to research the legality of Air BnB rentals in Barcelona. I seem to recall reading that Barcelona is one of the cities cracking down on such rentals.

I did find this from last November:

http://www.telegraph.co.uk/news/2016/11/24/barcelona-fine-airbnb-homeaway600000-offering-illegal-accommodation/

I booked all of our apts on booking.com for our family of five. I found that there were plenty of options to choose from. We are staying in the L'eixample area.

Issues with Airbnb and city of Barcelona are resolved and there are dozens of legal listings. The required registration number is often predominstely displayed on the listing. With it may come an in cash per head daily tourist tax payment for the city....about $1US per person a day and you may need to complete paperwork and leave a copy of passports as travelers are required to be registered with police when staying in any public accommodation. These details will be outlined on the listing. If no HUB number listed, you can email to request it prior to booking.
Sorry I can't recommend a place. I'll be visiting after you and in the Sagrada Familia area. My recommendation would be to go only with those with lots or reviews. You may also email and ask for a more exact location coordinate and then use Streetview for an initial visual check.

• The "issue" is not with the service of Airbnb and similar sites (Homeaway, Booking, etc) but with the non-compliance of some of these with local laws when they accept listings of apartments that haven't been registered and issued a permit to act as short term rentals. From the dozen or so portals, most have complied with the laws, only a few arrogant players have still not... but they will, or will be heftily fined -as some have already been. As a customer, simply make sure you rent a legally registered apartment: http://meet.barcelona.cat/habitatgesturistics/en/
• "a place walking distance to the sites"... I'm afraid that does not exist in Barcelona as the so-called "sites", or places that attract the interest of visitors both local and foreign alike, are not concentrated like in a theme park but spread across the city. There are different areas of the city where visitors choose to stay, each one for different reasons (closer to the airport, less crowded, less touristy, more bohemian, more historical, closest to the beach, etc). The most "popular" so to speak, are the neighbourhoods of El Gòtic, La Ribera, Santa Caterina, Sant Pere, Vila de Gràcia, Poble Sec, El Poble Nou, Sant Antoni... and also most of the neighbourhoods of the district of l'Eixample. Map of districts and of neighbourhoods.