During the Cold War, cities were seen as likely targets of modern total warfare and systems of civil defence were created to protect cities and their inhabitants. Yet existing civil defence histories have focused little on the specifically urban aspect, and urban historians likewise have paid civil defence little attention. Using Aarhus, Denmark, as a case-study, this article examines civil defence through planning, practices and materiality in a specific urban landscape. By analysing how civil defence was organized, performed and built in Denmark, the article sheds light on the mutual imbrication of urban planning, geography and materiality and local civil defence. I argue that through biopolitics, local civil defence authorities imagineered an idealized survivalist community of city dwellers who would pull together to protect and save their city and that this contributed to taming an incomprehensible, global, nuclear catastrophe into a manageable, localized, urban calamity.