The rise of fortifications in various border areas appears to reassert a renewed centrality of the linear border. Although the proliferation of walls, barriers and fences can be interpreted as a response to the crisis of the post-Westphalian model of state sovereignty, contemporary walls are first and foremost offensive rather than defensive devices. Secondly, the processes of fortification and militarisation of borders only seemingly provide the image of a sealed territory; in reality, contemporary borders are highly selective and porous, do not have a deterrent effect on so-called illegal migration and are conducive to the differential inclusion of migrants. In conclusion, the visibility and materiality of walls are constantly challenged by migrants’ mobility practices and struggles.