Ludwig Hilberseimer (1885–1967) is regarded as one of the leading theorists of the Neues Bauen (New Building) movement — and of modern, functional urbanism, in particular. Having emigrated to the US in 1938, he published The New City: Principles of Planning in 1944 after a twelve-year process of writing and translating. This text set out the content and fruits of his teaching at the Bauhaus (1929–33) in printed form. Hilberseimer had influenced the teaching of architecture at the Bauhaus for longer than figures like Hannes Meyer and Ludwig Mies van der Rohe, which makes it all the more remarkable that this text has only now been published in German for the first time. This critical edition reconstructs the intellectual context of the work and traces the complex process of its creation, using materials from Hilberseimer’s estate to reveal the extent to which ecological considerations informed this classic of modern urban design theory and suggesting how we might revisit this theory from a contemporary perspective.