Forget plaques and tchotchkes—the Berlin Wall has got to be the ultimate diplomatic souvenir, as slabs of the enormous, concrete barrier have made their way to spots around the world. More than 40 are on display in the United States, both privately and publicly; there’s even one here in Chicago at the Western Brown Line station. A tour of these spots comprises this deceptively high-concept documentary by nonfiction filmmaker Pacho Velez (Manakamana, The Reagan Show) and experimental filmmaker Courtney Stephens. They travel the United States in pursuit of locales where sections of the wall reside, more than 20 years after its eradication in 1989. Velez and Stephens do more than show the fragments; at various spots, they interview people they encounter about the experience of seeing, living near, or having acquired a piece of the iniquitous barrier, the speakers ranging from nameless (and sometimes even faceless) tourists to art collectors and administrators at civic and historical locations. Ultimately (and fittingly) the documentary illuminates not the history of the wall or how so many fragments of it came to the U.S., though that’s naturally a factor here. (Some home video and archival footage add gravitas, imbuing the aporetic inflection of the project’s aim with an appropriate reverence for the struggles faced by the east Germans.) Rather, it’s the myriad interpretations of the wall’s significance that exposes the mercurial and allegorical nature of history. This is complemented by the stirring 16mm photography and the studied distance with which Velez and Stephens interrogate the past.