Want to visit "Parque Güell"? One of Barcelona's most visited sight. One advice : book tickets online in advance because it's very likely to be fully booked when you arrive.
At "La Terrassa del Mar" you can find a fun outdoor area with slides and labyrinth for kids to play.
Although located strategically next to "Estación de Sants", Barcelona's main train station, the Espanya Industrial Park is not well known by people who live outside the Sants District. You might recognize it thanks to its characteristic tall towers that look like lighthouses.
The "Jardins de Tete Montoliu" is a large inside playground (interior d'illa) with a lot to space to have fun. It is also incredibly quiet.
When visiting a city with kids we often need to take a break from the sightseeing and just sit and relax for a while watching the kids play. If you think this sounds good then I have just the place for you: "Plaça de Vicenç Martorell"