Within the field of border studies, the Inner German boundary serves as a paradigmatic case of how provisional demarcation lines can harden into highly securitized frontiers. Originally delineated after World War II as an administrative division, it soon became one of the most militarized landscapes of the Cold War, marked by barbed wire, minefields, and forced relocations such as Aktion Ungeziefer (“Operation Vermin”). Beyond its role as a geopolitical and ideological divide, the border also constituted an ecological fracture zone: East Germany’s reliance on lignite, lax industrial regulation, and uranium mining generated severe environmental degradation with transboundary consequences for West Germany. The 1972 Basic Treaty and the establishment of the East–West German Border Commission in 1973 introduced pragmatic mechanisms of cross-border governance, including environmental monitoring, disaster coordination, and direct communication through Grenzinformationspunkte. Following reunification, the once-feared “Death Strip” was transformed into the Grünes Band, now Europe’s largest continuous ecological corridor, illustrating how former zones of division can be reconfigured as shared spaces of sustainability and cooperation.