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 public holiday, throughout the city and particularly the city center is filled with stands selling roses and books. The main example of this is Las Ramblas as is totally packed with people walking around looking for books and roses or simply enjoying the atmosphere.
The 23rd of April is also the Book’s day (Dia del Llibre) as it was the day that Miguel de Cervantes died (1616). There are lots of bookstalls around the city center 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 Spring day.
Tip: April 23rd is the only day of the year that the Palau de la Generalitat is open to the public. It is a magnificent building so it is a highly recommended visit. Big queues are expected so try to get there early.