The book Challenging the City Scale: Journeys in People-Centred Design, published by Birkhäuser Verlag, is the final result of the Human Cities_Challenging the City Scale 2014-2018 European project, where 12 partners from 11 European cities have developed strategies and tools to activate public spaces through bottom-up initiatives. Edited by Cité du design (Saint-Étienne) and Clear Village (London), Aalto University and Group X contribute to the publication with the Helsinki experimentation within the chapter “Sharing Spaces for Social Learning”. The book has been launched at the 13th Tallinn Design Festival in Estonia on September 13th.