A peculiar construction boom is in progress worldwide: border walls are being installed by wealthy countries at an unprecedented rate in order to control unwanted immigration by poor people. This Article asks why, almost a quarter of a century after the Iron Curtain came down, the walls are now going up again. It suggests a provocative answer: these separation barriers are a logical response by States to the way in which human rights law has been enforced in cases bearing on immigration. In other words, and counter-intuitively, the recent boom in border wall construction signals the success of the human rights tradition, rather than its failure to establish an alternative to territorial sovereignty. At the same time, this Article also uses the case study of walls to make a larger point on the intractability of the human rights regime that bears on immigration. Building on a systematic analysis of jurisprudence, I argue that human rights courts and quasi-judicial bodies utilize an arbitrary category— territory—to balance the policy interests of the individual non-national and the State. The result is essentially random from the perspective of both of these stakeholders. Walls make concrete a perverse side effect of this compromise: because the regime conflates access with territory, it disproportionately rewards strong young men who already have sufficient capacity (in age, gender, or resources) to scale the barrier, even if their predicament may not actually call for protection. But it privileges them only after they have risked themselves, and if they survive that risk at all. And so, at least when it comes to immigration, the human rights regime operates in effect as a natural selection mechanism. This is fundamentally unstable and unjust. There is no larger eternity than a door marked: closed today. Closed forever; no one's opening it, no one's coming. There are no clouds in the sky. Accept the verdict; sign. No one's opening. Go home, dream on. (Yehuda Amichai1) The distribution of membership is not pervasively subject to the constraints of justice. . . . [S]tates are simply free to take in strangers (or not) . . . . [T]he right to choose an admissions policy . . . is not merely a matter of acting in the world, exercising sovereignty, and pursuing national interests. At stake here is the shape of the community that acts in the world, exercises sovereignty, and so on. Admission and exclusion are at the core of communal independence. They suggest the deepest meaning of self-determination. (Michael Walzer)2