As an administrative tool of police reform, the introduction of house numbering in eighteenth-century Geneva was the result of a broad desire for urban transparency that resulted in the production of a new ‘regime of visibility'. This article examines how the logic of ‘number' transformed the way in which urban space was conceived, organized and governed. As a political technology, the spatial practice of house numbering enabled governmental officials to divide, count, identify and classify urban populations in order to regulate the spaces of circulation in the modern city. Although the city's house-numbering system is taken for granted by most of the town-dwellers today, the current study illustrates how these police techniques encountered considerable resistance when they were initially imposed during the latter half of the eighteenth century.