On a trip to Montreal Nestor Mir Planells started reflecting on the concept of 21st century library. The librarian was left with a lot of questions on how to handle the transition to technology and delocalisation in the contemporary city. Will the 21st century library still be a book container? On the other hand, will we only find digital information? Who will create the knowledge? During Placemaking Week Europe 2019, La Marina de València will host Nestor’s prototype of the 21st century urban library.