Why, just two decades after international celebrations of the fall of the Berlin Wall, are so many nation-states building elaborate walls at or near their borders? Why walls now, given growing global connectedness and given the general imperviousness of late modern powers -- from capital to religion to terror -- to physical blockading? How do walls shore up an imago of sovereign statehood and to what extent do they fortify reactionary national imaginaries? What do the new walls perform symbolically, materially, psychically?