Extended Abstract
Background and Objectives: Fortifications such as city walls and citadels allowed people to settle in their land and protected their lives from natural and human threats. The history of sedentism in the central plateau of Iran dates back to 10,000 years ago. In addition to this historical context, there are still surviving vernacular urban and architectural spaces in Iran. Meybod is a desert city located in the central plateau of Iran, where human settlement might have begun during the Medain period. The city was fortified with a city wall and a citadel known as Narin Castle. The advent of modern streets and the loss of significant parts of the city walls in recent decades have endangered the integrity and values of these structures. Meybod city wall and Sharistan are also facing these challenges. To ensure effective conservation, a comprehensive understanding of the evolution of urban and architectural heritage is necessary, along with an explanation of the changes that have occurred over time. Therefore, the research focuses on the following problem: “How have the developments and transformations of Meybod Sharistan influenced the evolution and changes of Meybod city wall?” The following objectives are addressed:
• Understanding the transformations of Meybod city wall in interaction with the changes in Sharistan to form its current structure.
• Identifying the position of Meybod Sharistan and Meybod city wall in different historical periods.
Methods: This research employed a case study approach and a descriptive-analytical method. Bibliographic research was conducted by examining historical written sources, national and international documents and charters, as well as urban and regional development plans of Meybod. Other data sources, including aerial photographs, were also considered. The results of this research were presented through schematic illustrations and simulations of the current and initial conditions using 3D modeling software.
Findings: Meybod city wall is an integrated architectural complex within an enclosed environment. It is built from two main vernacular earthen materials: Khesht (adobe) and Chineh (mudbrick). Its form and layout follow the topography of the land, defining the boundaries of Sharistan between two elevated terraces to the south and north. 
Three of the four main gates, portions of the ditches, and 11 towers of the complex remain intact. In the south, the city wall merges with Narin Castle (the citadel) through a three-layered rampart. The city wall also features unique elements. One is Bagh Khandagh (ditch gardens), where the former ditches have been repurposed as gardens and farmland. Another distinctive feature is the Darbands, small gates that facilitate passage through the walls to the ditch gardens outside the city wall of Sharistan. The transformations of the city wall and Sharistan are categorized into distinct time periods. Based on the earliest reliable evidence of its foundation, the categorization begins with the Sassanian period:
1. Pre-Islamic Era to the 14th century (Sassanid Period): Sassanid cities were characterized by a citadel (Narin Castle) and city walls, which served as living areas for the ruler and high social classes, while lower classes lived outside the walls. The first foundation of the city wall was likely established during this period. The introduction of Islam to Iran led to the collapse of the Sassanid social hierarchy, and all social classes began living within the city walls of Sharistan, which included the citadel (Narin Castle), a Bazar (market), and the Jame Mosque. The city wall underwent significant restoration due to the Mongol invasion, and a northern gate was likely constructed during this time.
2. 14th century to the early 18th century (Muzaffarid Period to the Early Qajar Period): During the Muzaffarid period, the city’s importance increased due to its strategic location on the route from northern to southern Iran. As a result, it remained fortified, and the Kasnava gate was likely built. After the Muzaffarid period, the importance of the city wall gradually declined, although its conservation continued.
3. 18th century to 1925 (Qajar Period): During the Qajar period, modern concepts such as private property rights were introduced to Iran, which led to investment in real estate. Consequently, the city expanded northward, with ditch gardens and Darbands (small gates) created, along with the construction of private towers. The defensive role of the complex diminished, and the northern gate was replaced with a Sabat (an arched walkway or corridor).
4. 1925 to 1979 (Pahlavi Period): Urban planning concepts from the modern era were introduced to Iran. The first modern streets were built, disrupting the traditional urban fabric. City walls became obstacles to urban development, and the first street in Meybod was imposed, dividing the city into eastern and western sections.
5. Post-1979 (Islamic Republic of Iran): Modern construction and street development continued until the 1990s, during which the city walls were still regarded as an obstacle to development. The establishment of local NGOs, the inclusion of the historic city on heritage lists, and the development of urban plans that took heritage values into account led to restoration and conservation efforts. However, many of these activities were carried out with some errors.
Conclusion: The changes and transformations can be divided into three stages:
1. Formation and Expansion: This phase spans from the initial construction to the eve of the Qajar period, reflecting a close symbiosis between the city wall and the city itself. During this phase, the city wall served both as a protector and a boundary, while continuous expansion, repair, and construction took place.
2. Completion: The developments in this phase are attributed to the Qajar period, characterized by a situation in which the function of the complex was relatively preserved. As a result, the city wall continued to protect the city limits. Both the city and the city wall adapted to new needs and experienced internal growth.
3. Decline: This phase coincides with the arrival of modern urban development trends in the post-Qajar period. The original function of the city wall was lost, and it was no longer intertwined with the city. Consequently, it became an obstacle to urban growth. This paved the way for modern constructions and the demolition of parts of the city wall by the 1990s. Eventually, a shift in perspective occurred, and the city wall began to be recognized as a heritage site with historical and cultural significance.