In the 1920s, the urban theory of Ludwig Hilberseimer (1885-1967) redefined architecture's relationship to the city. His proposal for a high-rise city, where leisure, labor, and circulation would be vertically integrated, both frightened his contemporaries and offered a trenchant critique of the dynamics of the capitalist metropolis. Hilberseimer's Grostadtarchitektur is presented here for the first time in an English translation. Its propositions encourage us to reconsider mobility, concentration, and the scale of architectural intervention in our own era of urban expansion.