Medieval fortifications remain among the most enduring material witnesses to the political, military, and cultural landscapes of the past. Castles and strongholds served not only as centers of defense but also as loci of administration, economic control, and symbolic power. While Western European castles have been extensively studied, the fortifications of Eastern Europe and the Caucasus regions that stood at the crossroads of empires, trade routes, and shifting frontiers have received comparatively less international attention. Yet these regions preserve a remarkable diversity of fortified sites, from citadels crowning volcanic promontories to walled urban centers and frontier garrisons. This session seeks to bring together scholars investigating the construction, function, and transformation of medieval fortifications across these interconnected regions. Contributions may explore themes including: architectural typologies and innovations; the role of fortifications in shaping settlement hierarchies and landscapes; military strategies and siege technologies; and the cultural meanings of castles as symbols of authority, identity, and resistance. We also welcome case studies that integrate archaeological, historical, and scientific approaches as bioarcheology, paleoenvironmental reconstruction, and materials analysis to illuminate the lived experiences of those who built, inhabited, and attacked these strongholds. By highlighting the fortifications of Eastern Europe and the Caucasus within a broader comparative framework, this session aims to foster dialogue on regional particularities as well as shared patterns of medieval defensive architecture. In doing so, it will contribute to a more inclusive understanding of medieval fortifications as dynamic elements of social, political, and cultural life across Eurasia.