Sasanian military architecture-especially its elevated stone fortresses-forms a fundamental part of Iran’s cultural heritage and played a key role in shaping the architectural strategies of later Islamic dynasties, particularly the Seljuks. Many Seljuk fortresses were erected directly atop earlier Sasanian structures, often retaining their layouts, materials, and defensive logic. This study presents a comparative analysis of the Sasanian military architectural elements, aiming to identify their transmission, adaptation, and innovation in subsequent periods. The evolution of this architectural tradition was profoundly influenced by Iran’s diverse geography. Mountainous areas required durable stone fortifications, while adobe structures were more suitable for plains. Iran’s strategic location-at the intersection of cultural, commercial, and military routes-combined with continuous threats from neighboring empires, fostered the development of complex and resilient defense systems. The research draws on a variety of sources: historical and geographical accounts by early Islamic scholars, travelogues by European explorers, and archaeological surveys by both Iranian and Western researchers. In addition to textual sources, material evidence-such as ceramics, construction techniques, and architectural remains-provides valuable insights into building practices. One notable transformation is the shift from thick Parthian dry-stone walls to narrower walls supported by rounded towers in the Sasanian period. The introduction of hydraulic lime mortars, likely brought by Roman prisoners of war, revolutionized construction on steep terrains. The widespread use of small river stones and regular masonry patterns in newly built cities reflects a deliberate move toward efficiency and durability. Late Sasanian architecture also reveals influences from Byzantine models in large-scale shelter designs. Monumental defensive structures such as the Gorgan Wall and the Moghan Wall exemplify the scale and ambition of Sasanian military planning. This preliminary study underlines the significance of Sasanian innovations and calls for further archaeological and architectural investigations to clarify their enduring impact.