Aachen embodies the complex historical strata of a European borderland. Founded by the Romans as Aquae Granni, a spa town centered on thermal springs and cultic practices, it emerged as a contact zone where sacred landscapes met imperial frontiers. Under Charlemagne, Aachen was transformed from a peripheral spa into the Carolingian political core, hosting imperial assemblies, receiving Byzantine and Abbasid envoys, and fostering the intellectual and artistic revival of the Carolingian Renaissance. Einhard’s Vita Karoli Magni underscores how the city’s natural springs both symbolized and sustained Charlemagne’s attachment, binding environmental features to imperial identity. Even as the empire fragmented after the Treaty of Verdun (843), Aachen retained symbolic centrality: between 936 and 1531, thirty German kings were crowned there, rooting legitimacy in a borderland setting that bridged core and periphery. In the modern era, Aachen has reemerged as a transnational hinge. The International Charlemagne Prize (est. 1950) and the Treaty of Aachen (2019) have recast it as a site of European unity and Franco-German partnership. Within the Schengen Area and Euregio Meuse-Rhine, Aachen exemplifies how border cities evolve from imperial outposts to integrative nodes, embodying borderlands as palimpsestic spaces of division, negotiation, and connectivity.