The article examines the discussion connected to the formation and approval of new extension plans for Turin in the mid-19th century. It shows that the issue of the limits of the city played a crucial role in many of these discussions. Institutions and landowners were involved in debates about both the new spatial limits of urban extension and the limits of public control over building activities. The intensity of the discussion may be read as the effect of a peculiar phase in the history of Turin, marked by strong institutional change and the emergence of private initiative in a land market previously controlled by the public sector. But the study of these discourses may also have something to teach about the growth of 19th century cities and the social and cultural forces which shaped it. Conflicts about urban growth dealt more often than is usually recognized with invisible, immaterial issues, such as the definition of a new symbolic geography of urban space.