Sant Jordi also brings with it temporary spaces for book exchanges. These improvised markets are organised in many of Barcelona's civic centres and libraries, and you'll find one in nearly every district in the city. Look for book-exchange markets in the Trinitat Vella library, the Can Castelló civic centre, the Riera Blanca civic centre, the Zona Nord library or the Sant Martí de provençals library. You know how it works: come with books you no longer want, and exchange them for ones others have brought. Most will likely be in Catalan or Spanish, giving you the perfect opportunity to learn or brush up on your language skills. However, with so many international residents in Barcelona, you might find just the title you've been looking for in your native tongue.