April 23rd is the feast of Sant Jordi (Diada de Sant Jordi), the patron Saint of Catalonia. The tradition is that the man buys the woman a rose and the woman buys the man a book, although this is not just between lovers, it is also between friends, workmates, … It is a very colourful day as you will see almost everybody carrying at least one rose.
Although Sant Jordi is not a bank holiday, city centre is totally packed with people walking around looking for books and roses or simply enjoying the atmosphere. As it is also Book´s day (Dia del Llibre) there are lots of bookstalls where you can even see writers signing their own books.
It is a very romantic day, although in recent years is getting more commercial, but still a very enjoyable day. Source: tourisminbarcelona