The cities of Cape Town, Christchurch, Hobart, Punta Arenas, and Ushuaia are formally recognized international gateway cities through which flows most travel to the Antarctic region. All significant engagement with the South Polar region is co-ordinated through them. By geographical placement and historical contingency, these cities have a special connection to their bioregions to the south. Today, the Antarctic region faces unprecedented challenges. These Southern Oceanic Rim cities, individually and as a group, are in a position to play an important role in defining how Antarctica is imagined, discursively constructed, and vicariously experienced. This requires elaboration of the more conventional roles they have played as 'gateway cities'. As this research report shows, these five cities are much more than gateways. They are intimately connected to the south in ways-historical, cultural, political, affective-that exceed the logistical and transport function implied in the notion of gateway. With the 'ice continent' taking on a new centrality in global public consciousness in the Anthropocene, these cities' relationship with the region to their south is likely to become an even more valuable part of their urban identity. As the future of the Antarctic hangs in delicate balance, this research project argues that these cities are key to securing the future of this fragile region. Antarctic gateway cities are urban centres that can embody the values associated with Antarctica-international co-operation, scientific innovation, environmental protection-and act as global stewards of the South Polar region. As Antarctic custodial cities these urban centres can strengthen an existing interlinked southern-rim network, to better learn from and benefit each other. The Antarctic Cities project has sought to shift the emphasis on the role and responsibilities of nation-states in Antarctica and pay attention to the roles and responsibilities of these five cities formally recognized as the Antarctic gateway cities. It has sought to summarize this change in conception and function by interchanging 'gateway' with 'custodian'. In this context, it seeks to inform decision-makers and citizens on how their Antarctic gateway cities can best effect a cultural, political, ecological, and economic transition towards becoming Antarctic custodial cities.