Abstract
Architectural remains are as the “foundation” of archaeological research, these evidence can be described with words, numbers and precise and clear drawings. But the interpretation of architectural remains and worldview contexts related to human social behavior are still problematic. Architecture is related to material remains, but we must remember that ultimately these remains reflect the customs and worldview of the respective societies. There is no doubt that the individual household unit changes successively over time to accommodate nuclear and extended families, groups, tribe, etc. Cheshme Rajab site is located in Lorestan province, Kohdasht County - Konani district, 500 meters north of the Symareh River, 6.5 km from the top of the Symareh dam, and in the cultural domain of central Zagros. It is considered one of the key sites for the study and cultural developments of the rural settlement period of the region and Zagros.  In April 2019, the second season of extensive (vertical-horizontal) archaeological excavations was carried out by creating three trench in the center, west and south of the site in order to know and be aware of the cultural developments in the region in the said Tepe. The current research is based on the presentation of the exploration results, the discussion of its architectural data analysis. This research  is done with a fundamental purpose and its data collection method is based on the field and library method, and in it, while introducing and describing the architecture of this site, we seek to answer the questions regarding the architectural condition of this site, such as whether it is right-angled and... Which period does the site belong to? Also, based on the results of the archaeological excavation, it can be said that in terms of the obtained works, it belongs to the late Neolithic and Chalcolithic Period.
Keywords: Symareh, Cheshme Rajab, architecture, Neolithic Period, Chalcolithic Period.

Introduction
The water catchment basin of the Symareh dam is located at the intersection of the common border of Lorestan and Ilam provinces. Symareh, having a different environment (mountainous, plain and hilly), located in the central Zagros basin and adjacent to the lowlands of Khuzestan and Mesopotamia, has always been the focus of different cultures. In general, due to the special biome and diverse geographical texture of central Zagros, this site has long played a key role between Mesopotamia and Khuzestan and the highlands of central Zagros. The changes of intra-regional (environmental) factors cause the abandonment or burial of villages and hamlets that were formed on the side terraces of the Symareh River, and these developments are important for archaeological research. The presence of small and large terraces of sedimentary deposits, fresh water springs, the use of pasture land, rock shelters, etc., are important factors for the emergence of settlements in this region in the prehistoric period (Introduction). et al., 2017: 3). In the meantime, the excavations of the Symareh dam basin have provided valuable information about Neolithic and Chalcolithic Period cultures. In the investigation and identification of the cultures of the Symareh dam basin, Cheshme Rajab site in 2007, by Abbas Moghadam and colleagues; the first season was explored by stratification but did not reach the virgin soil, the second season of archaeological exploration was carried out in 2010 by Abdul Reza Mohajeri Nezhad. According to archaeological research and excavations, most of the settlements during human settlements since prehistoric times have been located in line with water resources that have suitable environmental conditions. Therefore, the catchment site of  Symareh River is not exempt from this case. In 2007, the investigation and rescue excavations of the Symareh dam were able to investigate many ancient sites and clarify the time period of ancient times. Also, the Cheshme Rajab site is one of the important and key sites of the Symareh basin for investigating the process of cultural developments during the realization period of the Zagros region. One of the goals and necessity of the research in the Cheshme Rajab site is to investigate and analyze the architectural findings obtained from the Chalcolithic Period of this site. The main question of this research is trying to determine which cultural period the architecture obtained from Cheshme Rajab’s surroundings by examining the settlement style belongs to. Based on the results of archaeological excavations, it can be said that in terms of the obtained works, it belongs to the late Neolithic and Chalcolithic Period.

Research method
The current research has a qualitative and strategic system and is based on fundamental goals and is historical in terms of method. The method of data collection has been carried out in two ways: field and library. In the field method, the desired samples have been examined and studied. The basis of analysis relies more on internal information and findings, and the second method is a library that draws conclusions by matching and comparing data at the same time and by matching and analyzing them.

Discussion
The people living in Cheshme Rajab lived in rectangular houses. The main materials used in the construction of houses are materials such as crushed stone (river), mud mortar and plaster, which are taken from the natural bed of the region and due to the easy access and experience of the residents of the region, in angular and almost rectangular spaces, as a unit. They have used a building in rammed floor or rubble and almost regular clays and a mold that was a combination of straw, sand and river mud. According to the time frame of Cheshme Rajab, from the beginning of the Neolithic period, it seems that since this time, due to the easy access to stone, they have started to build buildings with stone carcasses, which have taken a step towards monotony (old village settlement). The obtained architectural remains indicate the construction of angular chambers made of crushed stone with a floor of rammed earth and sometimes cobblestones were used. The coherent architecture that was obtained from Pit 1 has not been observed in any of the contemporaneous sites in central Zagros, also in Pit 2, evidence of an industrial trench was found, which is unique in its time period and can be a sign of a specialized society. In this trench, several clay sherds were found, which were probably a sign of a spinning trench. Such Spindle Whorl in the Symareh basin were previously also reported from Chararo, but there was no discussion about the existence and acquisition of the trench (Hessari et al., 2012: 94), the emergence of these evidences either from the Rajab Spring or from Chararo itself. It shows the emergence of an advanced society that they created a spinning trench, although Henrikson, by studying the architectural structure of Tepe Segabi A in the Godin VII period, believes that this structure was a mass production trench and a skilled and expert group was engaged in it (Henrickson, 1988: 10) And later Badler and Rothman were also of the opinion that at the end of the Middle Chalcolithic Period and the beginning of the late Chalcolithic Period in the Godin VII period, Zagros-centric societies are passing from simple and equal societies to rank societies (Rothman & Badler, 2011: 80).Despite the fact that in the west of Iran, simple village-dwelling and herding communities live and we do not see evidence of social complexity and inequality in them (Mohammadi-Qasarian, 2021: 19), at the same time, in the northern and southern Mesopotamia, we see large site that reach up to 15 hectares in size. (Trentin, 2010). The round temples in Erpachie and the big temples in Eridu indicate the formation of societies with social complexity (Stein, 2012: 130). This issue is also true in the southwest of Iran (Holl, 2002: 178), while no signs of social complexity and progress can be observed in central Zagros (except Cheshme Rajab & appeh Chār Ārou) at this time, even the spread of Dalma pottery and the similarity Together, they raise the hypothesis for some researchers that maybe this pottery was produced in a certain center and was distributed throughout Zagros (Henrickson & Vitali, 1987: 40), but so far there is no work that confirms this hypothesis. Among the materials found in Cheshme Rajab, it can be a proof of an advanced society.

Conclusion
The Symareh River is a river that drains the entire region and the change in its behavior has had a tremendous impact on the geology of the region and the way humans have settled. Due to the strategic location of the Symareh Valley in the west and southwest of the Iranian plateau, it has been considered as an intercultural communication route since ancient times. The location and geographical conditions (Symareh alluvial valley, great heights of Kabirkoh and its pastures, Symareh river, alluvial and rich lands of the region) have provided ideal conditions for agricultural life and animal husbandry in the region. According to the obtained architecture, the residents of Cheshme Rajab have settled in right-angled houses with a rectangular layout and the use of natural materials of the site. The main materials used in the construction of houses are irregular rubble and molded clay with mud mortar. Inside the architectural spaces, there are traces of ovens, food storage pots, the existence of their large objects and counting objects, which are direct evidences regarding the storage system of the residents of the site during the Chalcolithic Period.An architectural space for industrial activities with clay flooring, clay Spindle whorl, works of pottery kilns, welding kilns and pottery that fell due to high heat, which shows that architectural spaces were used for industrial activities in addition to residence. During the Chalcolithic Period, like in other sites, especially central Zagros, the inhabitants of the site gathered bodies under the floor of residential spaces and buried small decorative objects and children inside burial vats. Other findings obtained in the site, such as obsidian blades, show the connection of the residents of this site with other places (Northwest and Anatolia) and the presence of clay Spindle whorl are direct evidence of the advanced spinning activities among the residents. Also, according to geographical conditions and environmental factors, the existence of extensive pastures in the site and spinning spindles are indirect evidences related to animal husbandry activities among the residents of the site.