A Physio-Spatial Typology of Iran’s Extra-Urban Caravanserais Based on a Study of Their Architectural Role

Introduction:
 Traditional Iranian architecture, as a reflection of the continuous interaction between humans and the environment, has always been shaped with an “eco-friendly” and “introverted” approach to environmental challenges. In the meantime, caravanserais, as one of the most vital cultural and economic infrastructures in Iranian history, are known not only as resting spaces but also as symbols of climate-adaptable architecture.
The Purpose of the Research:
This research was conducted with the aim of developing a precise typology of the architectural plans of Iranian caravanserais.
Methodology:
 The research method of this study is analytical and interpretative-historical, and in terms of its purpose it is applied, and the method of obtaining information is deductive reasoning. The reasoning of information to achieve findings is logical and rational. The method of collecting information is library and field collection. The statistical population of the caravanserais studied in this study is all the caravanserais of Iran. The selected population includes a wide range of caravanserais with diverse designs. In this study, more than 300 caravanserais were studied, of which one sample was selected for the study. Study samples were selected from all over Iran and according to components such as; climate, geometric form, geographical location, and having specific architectural patterns. After identifying and completing the basic information of the building plan, the samples were documented and then their architectural typology was analyzed. In this study, the basis of the typology is the horizontal plan map of the caravanserais. In this typology, the geometric form, general shape, and architectural body are the components of the typological study. The sampling method is purposeful and non-probability. The selected samples are generalizable to other statistical populations. The research tool includes the two-dimensional AutoCAD program. A professional camera was used in the field surveys.
Findings and Discussion:
Over the centuries, Iranian caravanserais have experienced a gradual process of evolution in their architectural elements and plan patterns, which have been influenced by geographical, cultural, social and security factors. Based on the geometric typology approach, eleven main types of plans (including square, rectangular, circular and octagonal) can be identified throughout Iran, with their roots dating back to the pre-Islamic and Islamic eras. Although specific types such as the “mountainous roofed” plans in the northwest and the “Persian Gulf coast type” in the south are concentrated, other patterns such as courtyard, porch and columned caravanserais are scattered throughout the geographical area of ​​Iran; so that the courtyard plan is recognized as a dominant and pervasive pattern even in hot and humid regions. Structural similarities and landscape features in caravanserais along a route indicate the existence of architects, founders, or organizations that were codified in the design, although the creativity of architects has always created subtle differences despite general similarities. In addition, the characteristics of the historical period and functional needs have played a decisive role in the evolution of these buildings; for example, the change in the function of towers from defensive to decorative in the Seljuk period, the replacement of the porch with the portico, the evolution of the pediments in the Safavid era, and the simplification of designs in the Qajar period all indicate the adaptation of architecture to the conditions of the day. Ultimately, this evolutionary process shows that the form and function of caravanserais have always sought to respond to the growing needs of travelers and improve functions (such as improving access to camel huts or adding water fountains) in order to play their role as an efficient basic plan.
Conclusion:
 In response to the research question, it should be stated that the ratio of length to width of the open space, for example the length and width of the central courtyard, is directly related to the formation of the overall form of the plan and the courtyard and the spaces around the courtyard. In caravansaries where the length to width ratio is equal, the number of rooms is equal on each side of the courtyard and their number is equal. In geometric ratios where the length to width is not equal, the number of rooms is not equal on each side. The ratio of length to width of the open space causes the formation of different dimensions and sizes of the spaces around it and shapes its spatial arrangement. The study of the similarities and differences of the architecture of caravansaries has led to the identification of the similarities and differences of the physical aspects of the caravansaries. The study of the studied caravansaries shows that the similarities of the caravansaries that are on a common social, cultural and economic path are greater than their differences, and these common and similar aspects can be used in the physical restoration and recovery of the lost spaces of the caravansaries. This research focused on the typology of the architectural plan of the suburban caravansaries of Iran. The typology of the architectural elements of caravanserais, such as the entrance, vestibule, porch, central courtyard, rooms, and camel sheds, requires further research to complete the typology of the architectural space of caravanserais. It is hoped that further research will be conducted in this area. The limitations of the present study were the lack of architectural maps of the current state of the caravanserais, the lack of access to all caravanserais, the destruction of a large part of the spaces of the caravanserais, and the lack of cooperation of the custodians of the caravanserais for visits in some cases.