This article showcases how a feminist perspective provides novel insights into the relations between military heritage/history and national security politics. We argue that analysing how gender and sexualities operate at military heritage sites reveals how these operations dis/encourage particular understandings of security and limit the range of acceptable national protection policies. Two recent initiatives to preserve the military heritage of the Cold War period in Sweden are examined: the Cold War exhibits at Air Force Museum in Linköping and the redevelopment of a formerly sealed off military compound at Bungenäs, where bunkers have been remade into exclusive summer homes. By combining feminist international relations and critical heritage studies, we unpack the material, affective and embodied underpinnings of security produced at military heritage sites. A key conclusion is that the way heritagization incorporates the ‘naturalness’ of the gender binary and heterosexuality makes conceptualizing security without territory, or territory without military protection, inaccessible. The gendering of emotions and architectural and spatial arrangements supports historical narratives that privilege masculine protection and reinforce a taken-for-granted nativist community. A feminist analysis of military heritage highlights how gender and sexualities restrict security imaginaries; that is, understandings of what is conceivable as security.