Despite a multiplicity of ongoing conservation activities, European biodiversity loss is still ongoing, caused mainly by a high level of habitat loss and fragmentation. Along the former Iron Curtain, wilderness areas and valuable natural refuges were preserved across Europe from Fennoscandia to the Black Sea. Initiated in 2003, the European Green Belt (EGB) aims to create, maintain, improve and extend this trans-border ecological network. In this paper we discuss the ecological functions of the EGB and provide an overview of research potential, activities and needs along the corridor. The implementation of ecological networks within planning instruments and European strategies on green infrastructure and wilderness underlines the importance of the EGB. Fulfilling its function as the backbone of an ecological and social network on different levels, the EGB triggers intensive collaboration between neighboring countries and provides new chances for formerly marginalized border regions to choose a sustainable path for their further development.