Typologies, published in 2003 as the catalogue of the Kunstsammlung Nordrhein‑Westfalen, contains 130 groups of individual photographs of the same types of buildings, arranged as tableaux. The Bechers prepared a total of twelve groups of subjects of industrial buildings, ranging from water towers to factory buildings, organized into typologies with varying numbers of examples. The abundance of material condensed in this way—1,528 photographs in total—allows for a comparative view and unites scientific systematics with aesthetic empiricism.