The Arctic, like all extreme environments, has long constituted a privileged space to the study of Man-Nature relationship. However, researchers have been slow to take into account the fact that the majority of boreal residents is urban and that northern cities are, most often, essentially populated by non-natives. The Arctic certainly no longer represents an isolate; globalization and climate change are profoundly modifying this strategic space for humanity. In this context, the fate of polar localities benefits greatly from being considered from the holistic perspective of geographers. After a "Scientific Positioning" section shedding light on the "boreal city" as an object of research and the issues it raises for global society, this work looks again at the processes involved in "Populating the Extreme", drawing on key concepts in the discipline (determinism, resources, settlement, (an)ecumene, frontier). The next part, 'Urbanising the extreme, integrating it', puts the notion of the polar city to the test of the categories of geographical analysis and opens up the debate of a possible convergence towards the idea of the 'global city'. Finally, taking a temporal and multi-scalar approach, the question of 'the polar town as a vulnerable place is raised. Indeed, polar urban locality, uncertain of its future, seems intrinsically more vulnerable than the mid-latitude city because i) it is located at the edge of the ecumene, far away from the major centers of the world system, and will remain so for a long time to come, ii) in physical and human environments that are harsh for humans, and iii) undoubtedly among the most fluctuating on the planet. Ultimately, the current dynamics of boreal urban areas show a differentiated process of de-nordification, provided we accept that the North cannot be defined solely by a single physical criterion.