Since 1959 Bernd and Hilla Becher have been photographing imperiled industrial structures such as pit-head frames, water towers, blast furnaces, cooling towers, gas tanks, and silos. As documenters of the industrial era in Europe and the United States - an era now drawing to a close - they are not only photographers, but industrial archaeologists, salvaging testimonies of past developments in the form of readable documents for posterity. At the same time, the Bechers could also be called conceptual artists, as their photographs reveal the meaning and transformative character of structure.