The immigration crisis that affected the European Union and its member states in 2015 and 2016 and manifested itself in the influx of over a million refugees has not only deeply divided Europeans in terms of the proposed response, but also challenged the integration project itself. Control over human movements has become a symbol of national sovereignty and security again, and raised questions about the shape of the Union and structure of its competences. Migration and asylum policies have been confronted with the Schengen provisions and the space of free flow of people undermined by rebordering tendencies. The aim of the presented volume is to investigate the current challenges for the European Union resulting from the immigration crisis, especially with regard to the external and internal borders of the Schengen Area. It contains more general reflections on the problem as well as contributions referring to current member states' views on border protection, boundary (re)fencing and territoriality, alongside historical reflections on the "defender of Europe" concepts, together with their current manifestations. The authors ventured to investigate the consequences of the crisis for the Schengen Area and the territorial shape of the European project.