historicizes the concept of public health in the context of the fourteenth- and fifteenth-century urban Low Countries. It begins by outlining how then-prevalent Galenic or humoural theories defined health, and how such ideas were employed by various Netherlandish governing bodies through a focus on spatial interventions. Analyses of street paving, water regimes, fire prevention, and military safety demonstrate how health interests involved mitigating communal risks through adaptations in the built environment. Preventative measures thus shaped cities’ morphology from the outset of urbanisation. Town governments were willing to invest major sums to improve safety and well-being and realized a program aimed at preserving flow. The creation and adaptation of complex infrastructures also stimulated further sanitary and maintenance routines. These required coordination concerning the division of responsibilities and tasks, and the policing of such arrangements.