The Demilitarized Zone (DMZ) landscape between the Democratic People’s Republic of Korea and the Republic of Korea is currently the most dangerous and heavily fortified territory in the world and has produced a series of continuously linked brownfield lands on a divided Korean Peninsula through the continued intense presence of military troops and equipment, a significant amount of defense infrastructure, and pollutant buildup over the last seventy years. The political and social reunification of the two Koreas may occur in the coming years and any work in the future to address the landscape of a unified peninsula would be required to carry out in the DMZ. The work includes a complete characterization of the land area and water bodies and the existing military infrastructure and abandoned equipment, with the proposed remediation of soils, groundwater, and drainage systems as well as the concerns of brownfield land reuse, adding new industrial manufacturing to the area, the increase of tourism into the region, and the development of both traditional and new forms of regional energy generation. The brownfields in the DMZ can be considered an extreme version of the more conventional post-industrial sites that are addressed in other urban or ex-urban venues through the methods and conventions of brownfield regeneration. Or indeed it may become a new type of brownfield site — the “brownfield border” — with its own characterization, on-site pollutants, and methods to address its ongoing remediation and reuse programs. The intention of this paper is to examine the DMZ through a recent academic study carried out through a graduate design studio at Harvard University focused on the outcomes of unification on the Korean peninsula, the remediation of border landscapes as a new type of brownfield practice, and potential planning and design of alternative futures.