Based on an urban legend and only celebrated in Catalonia! Students dress up as either princesses, knights, dragons, or their favorite character from a book. It is also customary for gifts in the form of books and roses to be exchanged between friends, loved ones, etc. 

We went to the festival in Seville which is only held one week during April. The far is what you would expect of a county fair, except flamenco (traditional Spanish dresses) are worn and traditional flamenco dancing takes place. There are massive tents with music and flamenco dancing.