On La Diada de Sant Jordi! Barcelona’s streets are covered in red and yellow. You can see the Catalan flag everywhere… buses, balconies, store fronts. Sant Jordi is like the catalan version of Valentine’s day, traditionally men give women roses and women give men books.
Las ramblas and Plaça Catalunya gets filled with rose and book vendors. Even though is fun to walk the streets of Barcelona on Sant Jordi, they are so packed that it can be a bit overwhelming. I find Sant Jordi the perfect day to actually head to Tibidabo, or the north side of the city where the celebrations are more laid-back. In 2010 me and Iraide decided to celebrate it at Sala B, a bit posh for our taste but it was free so we headed there with rose in hand.
For more historical information on Sant Jordi go to Don Quijote: http://www.donquijote.org/culture/spain/society/holidays/ladiada.asp