Book excerpt: European cultural heritage is inherently complex and layered. In the past, conflicting or controversial perspectives on different historical memories and experiences have been colliding in the rich cultural landscape of Europe and continue to do so in the present. Contemporary projects of re-activation of contentious spaces seem to challenge both the traditional design parameters and the role of spatial practitioners. They require new strategies that effectively mix top-down and bottom-up impulses, through a new design approach that is still in search of a clear definition. Contested Spaces, Concerted Projects collects the stories of some selected cases of difficult built heritage, in order to highlight the most innovative methodologies of re-activation, by which architects, artists, designers and collectives have developed new participatory public interfaces.