Working together as photographers since 1957, Bernd and Hilla Becher have become known for capturing endangered architecture quickly vanishing from the modern landscape. By the end of the 1960's they were part of the conceptual art movement in view of their minimalist approach. "Bernd and Hilla Becher: 4 Decades" follows the couple through their retrospective exhibition at Berlin's Hamburger Bahnhof Museum while they discuss their beginnings as documentarians of 19th century industrial architecture.