Sustainable Development (SD) in the Danube River Basin needs an Interdisciplinary approach. Researchers must be able to identify, analyse and take into account the legacies of the past and the long history of human interactions with the environment in this densely inhabited region. This introductory contribution to DIANET 2013 maps the 7 pillars of the EU strategy for the Danube onto the ‘magic triangle’ of SD. Finding solutions requires understanding the present situation through the study of socio-natural sites. Such sites form by interaction of humans and the river system. Practices result in material arrangements which are created and kept in working condition by human actions. Benign or wicked, short- or longstanding legacies can be distinguished, their fate determines the potential for sustainable futures.