This article deals with the change in safety requirements and technological possibilities in the course of industrialization by looking at the establishment of street lighting in Bielefeld in the 19th century. As will be shown, the development from oil to gas lanterns coincided with a change in the security needs of the urban middle class. It was the technical possibilities of gas lighting to penetrate the urban space at night that made marginalized groups of people who were perceived as a (...) security risk visible. This, together with the bourgeois internalization of the disciplinary effects of light, made this infrastructure possible in Bielefeld. While the urban populations of the pre-modern and early 19th century were still skeptical or dismissive of lanterns, by the mid-19th century their installation was already part of decidedly urban bourgeois demands for more safety in the areas of personal, economic and traffic safety. The lantern thus changed from an instrument of pre-modern visibility to an instrument of constant visibility in the modern age, which at the same time led to new lines of conflict when the expansion and extension of lighting was not as comprehensive as demanded by the urban bourgeoisie. In addition to the changes and conjunctures of security needs in the course of industrialization, Bielefeld also shows that an internalization of the concept of sovereignty by no means meant the absence of conflict. On the basis of administrative acts and petitions, the history of Bielefeld’s street lighting is placed in a larger transformation of security, technology and urban spatial design from the perspective of historical security research, drawing on Foucoult’s concept of gouvernmentalité. The results show that the history of technology and infrastructure can significantly deepen and contextualize the findings of historical security research. The use and expectations of technology were an essential part of a new understanding of security, as well as the socially segmented organization of urban space through a sometimes precarious alliance of different groups of actors. (shrink)