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Sajadi A. (2026). Re-identification of Falak-ol-Aflak Castle Based on Archaeological Excavations and Architectural Features. Athar. 48(1), 29-56. doi:10.61882/Athar.2085.1766.14
URL: http://athar.richt.ir/article-2-2085-en.html

Abstract
Falak-ol-Aflak Castle stands atop a natural bedrock outcrop in the center of the Khorramabad Valley. Throughout its turbulent history, this ancient fortress has undergone repeated phases of destruction and reconstruction. Consequently, its earliest structural phases have been lost, and its physical form has been so profoundly altered that archaeological investigation is essential for its historical re-identification. The existing literature on this structure relies chiefly on brief historical mentions or repetitive descriptions of its current state. To address this gap, this study employs archaeological excavation and a descriptive-comparative-analytical approach to interpret findings from stratigraphic soundings, thereby reconstructing the complex’s formation and structural evolution. Specifically, this paper addresses two key questions: (a) how was the initial structure established on the uneven rock topography? and (b) how did its architectural components and spatial configurations develop and expand over time? The findings indicate that the fortress underwent continuous physical transformations. To level the southern sections with the higher northern areas (conforming to the natural profile of the outcrop), the builders constructed a massive retaining wall, creating a flat foundation for the castle. Furthermore, this study reveals that a highly sophisticated engineering system was integrated within the fortress to manage water supply, distribution, and wastewater drainage.
Keywords: Fortress, Falak-ol-Aflak Castle (Shapurkhast Castle), Khorramabad, Architectural Evolution, Water Management.

Introduction
Falak-ol-Aflak Castle, one of Iran’s most prominent ancient fortresses, represents a continuous architectural trajectory of defense, protection, and restoration. Situated within the Khorramabad Valley, the fortress shares an intrinsic socio-spatial relationship with a network of surrounding historical settlements, most notably the ancient cities of Simashki, Shapurkhast, and Khorramabad. The historical longevity and strategic significance of this stronghold were dictated by three primary factors: highly favorable ecological conditions that sustained human settlement within the valley; a critical geographical position at the intersection of major transit routes connecting the central Iranian plateau with Mesopotamia and the southern and western regions; and key natural defensive features, characterized by a steep limestone cliff flanked by a river and encircled by mountain ridges. Consequently, this intersection of environmental and strategic advantages ensured long-term cultural continuity.
Depending on fluctuating socio-political dynamics, the castle assumed diverse administrative functions, serving successively as the seat of local governance for the Almuyids and the Pahla region during the Parthian and Sasanian eras; the governmental center of the Hasanuyid dynasty during the Buyid period; the administrative capital of the Atabeks of Lesser Lur during the Mongol and Ilkhanid periods; and, ultimately, the headquarters of the Governors (Wālīs) of Lorestan from the Safavid era until the late Qajar period. Utilizing a descriptive-analytical methodology grounded in archaeological and architectural data, this study investigates the construction and structural evolution of Falak-ol-Aflak Castle. Specifically, it addresses three primary research questions: (1) what taphonomic and construction processes shaped the formation of the fortress’s initial core; (2) what were the primary architectural components, spatial configurations, and subsequent phases of physical expansion; and (3) how were the internal water supply, distribution systems, and wastewater drainage networks organized and engineered over time?

Discussion
Geophysical studies indicate that the bedrock foundation of Falak-ol-Aflak Castle is highly irregular and sloped. These data confirm that the natural topography forms a longitudinal ridge with an east-west orientation, which gradually decreases in elevation from north to south along a gentle slope. Accordingly, throughout various historical periods, builders undertook extensive wall construction and foundation masonry on the eastern, southern, and southwestern sides to establish a level, uniform surface for the superstructure. In this regard, archaeological excavations and stratigraphic soundings (sondages) have verified the existence of multiple occupational horizons and enclosures within Falak-ol-Aflak Castle, dating from the Elamite and Median periods, through the medieval Islamic era, and up to the Qajar period.
Furthermore, archaeological excavations have revealed the hidden sub-surface layers of the castle’s water supply, distribution, and wastewater disposal systems, which were executed with remarkable engineering precision. Through accurate calculations, the designers of the hydraulic system managed to secure a sustainable and permanent water source by excavating a deep well directly into the bedrock. A key feature of this system is that, although the well opening was originally situated at the lowest point of the rock formation, the builders raised its operative height from −7 meters to +4.30 meters relative to the castle’s main floor level by constructing a robust stone and brick shaft wall. This artificial elevation enabled the gravity-fed distribution of water to all parts of the complex.
The extracted water was first directed into a regulation and distribution basin, from which it was channeled to the eastern and western sectors of the castle via two main ceramic pipelines (tanbūsheh). The western branch supplied the cisterns and the bathhouse located in the northwest corner of the first courtyard, while the eastern branch fed the pools situated in the second courtyard.
The wastewater disposal mechanism exhibited the same level of engineering sophistication. The system directed wastewater through ceramic pipes and channels toward five absorption wells, each measuring 888 to 999 meters in depth, strategically located at the corners of the castle. From these wells, the wastewater was channeled out of the castle grounds through brick-lined conduits. Archaeological evidence—including robust foundation work, the standardized arrangement and quality of the bricks, the specific mortars utilized, the protective plaster coverings over the channels and ceramic pipes, and the thickness of the pool walls—collectively attests to the high technical standards and structural reinforcement of these hydraulic features. Moreover, this sub-surface network served a dual function, providing both drainage and ventilation. By generating continuous airflow, it successfully mitigated rising dampness and kept the underlying structural layers dry.

Conclusion
Geophysical studies indicate that the bedrock foundation of Falak-ol-Aflak Castle is markedly sloped and irregular. The data confirm that the rock topography forms an elongated ridge with an east-west orientation, gradually decreasing in elevation from north to south along a gentle incline. Accordingly, builders in different historical periods employed retaining walls and foundation-leveling techniques on the eastern, southern, and southwestern sides in order to create a stable and uniform platform for construction. Archaeological excavations and stratigraphic trenches have substantiated the existence of multiple fortification walls dating from the Elamite and Median periods through the medieval Islamic era and into the Qajar period.
Furthermore, archaeological investigations have revealed sophisticated concealed systems for water supply, distribution, and wastewater management, all of which were designed with remarkable precision. Through careful calculations, the castle’s hydraulic engineers succeeded in establishing a permanent and sustainable water supply by excavating a well into the bedrock. A particularly notable engineering achievement concerns the location of the well mouth at the lowest point of the rock formation. To generate sufficient hydraulic head for water distribution throughout the castle, the builders constructed a stone-and-brick wall that raised the well mouth from −7 meters to +4.30 meters relative to the castle’s floor level. This engineered elevation enabled gravity-fed water flow to all areas of the castle.
The extracted water was first directed to a regulation and distribution basin and was then conveyed through two main ceramic pipeline systems to the eastern and western sections of the fortress. The western branch supplied the reservoirs and baths in the northwestern part of the first courtyard, while the eastern branch fed the basins in the second courtyard. The wastewater disposal system demonstrated a comparable level of engineering precision. Wastewater was directed through ceramic pipes and channels toward five absorption wells, each measuring 888 to 999 meters in depth and located at the corners of the castle, before being conveyed outside the complex through brick-lined channels.
Archaeological evidence—including robust foundation work, precise brickwork patterns, high-quality mortar compositions, protective linings for the channels, coatings for the ceramic pipes, and the thickness of the basin walls—attests to the advanced technical standards and structural reinforcement of these hydraulic installations. In addition, this subsurface network served the dual functions of drainage and ventilation. By facilitating air circulation, it helped control moisture and maintain the dryness of the underlying layers. The blockage of these channels in later periods has been identified as a primary cause of moisture infiltration into the upper layers and walls. Consequently, the complete reopening and restoration of this drainage network should be regarded as an essential measure for the sustainable preservation of the structure.