Abstract
In the history of architecture, one of the elements to transfer the vertical forces in buildings has been columns. They appeared in various forms depending on the nature of forces, architectural styles, available materials and joints applied. Examination of columns may revive and reveal certain parts of the lost knowledge of Persian architecture. Also, such an examination may help to categorize columns in terms of form and structure. The final form of the stone columns in pre-Islamic Iran has been directly influenced by their size and form of the trunk, base as well as capital. In this regard, columns have been often examined only in case studies. The present article, however, has studied the stone columns in pre-Islamic Iran in terms of geometric aspects. Data were mainly gathered based on library sources and field studies. In order to do a systematic classification, the stone columns were photographed. This article aimed to study the impact of form and size on the structure of the stone columns in pre-Islamic Iran. The results implied that the forms of base and shaft in stone columns of ancient Iran were mainly influenced by the vernacular motifs common at the time; bases of the stone columns were in cubic form or in the form of inversed vase. Similarly, the shafts of the columns were in simple, fluted and gadrooning forms. However, formation of the capitals is an adoption of forms found in columns of other civilizations. The forms include floral, zoomorphic a human images. 
Keywords: Geometry in Architecture, Structure of Stone Columns, Persian Monuments.

Introduction
Architecturally speaking, the formation of columns might be attributed to the idea that a given space was supposed to be extended. Columns transfer the weight load of the roof to the ground. At the same time, some archeologists believe that columns appeared when large flat roofs were built (Firouzmandi, 2008: 29). The oldest columns in Iran date back to the 6th millennium BC. Certain examples of which can be seen in western and North-west archeological sites of the country (Rezaienia, 2008: 329). The existence of columns went on to subsequent eras. However, since some of them were made of wood they did perish and only their stone bases survived (Firouzmandi, 2008: 29). The oldest examples of stone columns can be found in Median catacombs. This trend can also be observed in next eras and even in given monuments which columns played no structural role, columns embedded in walls were used. Geometrically, the stone columns used in pre-Islamic Iran functioned not only as structural element, transferring vertical forces, but also as architectural decorations presenting beautiful images in spaces. Hence, examination of the stone columns may help reveal the ancient architects’ capabilities to transfer forces structurally and to form architectural spaces aesthetically. So, in this study, the following questions are raised: Are any specific geometric proportions between forms and motifs used in column capitals of the pre-Islamic Persian monuments? Which kinds of geometric forms have been used more commonly in Persian column bases? What are the most commonly used geometric forms in the structure of Persian ancient columns?

Research Finding
One of the oldest usages of stone columns can be observed in columned halls in Māni sites. Hassanlou hill is a prime example in this respect. The survived monuments from Median era in which columns have been used can be divided into two groups: The first includes certain columned halls like those existing in archeological sites. The second includes Median catacombs.In terms of functional columns, Median  catacombs can themselves be divided into two groups: The first includes catacombs which have free columns in entering gate. The second group includes catacombs which have half-columns in entering gate. Columns in Achamenid architecture played more important role compared with earlier eras. The column bases appear in different forms including cubic and bell-shaped the latter of which are different from each other in terms of patterns and motifs applied. The trunks are either smooth or fluted. In addition, in Achamenid era, the column capitals appear in a variety of animal forms including bull, lion, horse, griffin and bull-man. The columns built in Seleucid era have been adopted from Roman order. Columns in Arsacid era can be grouped into three classes: Greek order, Persian order and vernacular style. The columns adopted from Greek-style generally appear in three common Greek orders: Corinthian, Doric and Ionic. In addition, the columns adopted from Achamenid style have cubic bases and capitals representing two animal heads in opposite directions. Columns in vernacular style represent square or octagonal trunks with or without patterns. Columns in Sassanid monuments, however, are the continuation of those in Arsacid monuments in form and style. The most commonly used capitals are in the form of truncated pyramid. The upper base of the pyramid is square in form and the lower one is circular decorated with repetitive animal or floral patterns. There are, of course, capitals adopted from Corinthian order. The trunks survived of the Sassanid columns are in simple, fluted or spiral forms with or without relief pat. 

Conclusion 
Column capitals in ancient Persian architecture include a variety of forms and decorations. Some of the forms like spiral patterns may play decorative role on the trunks. However, the spiral forms may only appear on capitals. Also, column bases are mainly cubic, bell-shaped or circular in form. Cubic bases are more common which appear in different forms visible in all but eras examined. In terms of form and decorative elements, column capitals in two Achamenid and Arsacid eras are more similar to each other than those in other eras. Other than decorative forms used in the bases, trunks and capitals, geometric patterns have been also used as decorative elements including floral, animal and human ones. Of course, floral forms have been most commonly used. With respect to the trunks, smooth circular trunks have been common in all eras studied. They may appear with or without fluted or spiral forms. Despite the importance of columns in pre-Islamic Persian architecture and their role in forming columned spaces, no comprehensive examination, in terms of geometric classification, has been made in this regard. In this study, the components of Persian stone columns in different pre-Islamic eras were classified geometrically. Other researcher may carry out similar examinations on architectural columns in Islamic era, classify them and determine the similarities and contrast. 

Abstract
Using the column element provided the necessary context to extend the architecture spaces. According the archeology findings the north-west area of Iran, due to the existence of abundant wood and stone resources has been leading using this element. In view of the remaining of the ancient columned buildings, the importance of column in the past is understood. Also during the Islamic era the element play a key role in the buildings of this region. In the Ilkhanid and Safavid era due to the climatic and cultural reasons, stony and wooden columns were used with abundant decorations with capital and base plinth in some mosques of Azerbaijan. It seems that Asnagh and Jamalabad Mehrban mosques are the start point of columned architecture with laborious decoration that in the following they reach to peak beauty in the Safavid columned palaces. The present article, on one hand, studies the process of column evolution in this region and, on the other hand, looks for the origin of the architecture tradition of decorative columns used in the mosques and palaces of Safavid era such as Ali Ghapoo in Isfahan, Bonab and Maragheh. The data gathering method include field visits, recording and documenting the data that finally was analyzed using descriptive-analytical method and using library studies. 
Keywords: Architecture, Azerbaijan, Column, Asnagh Mosque, Jamalabad Mosque.

Introduction
Architecture of every nation is a reflection of its thought and economic situations. The climate circumstances, beside these factors, also play a role an essential role in the formation of architecture. Materials and decorations also have a close relationship with these factors. Using column in the great building has a long history. Column is designed mainly to support the heavy load of roof and generally plays the role of strength and beauty of a building. In the ancient hills such as Yaniq Tapeh probably to cover the ceiling of the circular rooms the central columns have been used. The columned halls of Hasanlloo (Dyson: 1989), Nooshijan (Stronach:1978), Goodin Tapeh (Young: 1969), Babajan (Goff: 1969), the Mad’s catacombs and Achaemendis palaces (Sarfaraz and Firoozmandi, 2006), Parthian and Sassanid temples (Herman, 2008) and palaces represent the use of column in the past architecture that shows the importance of column in the pre-Islamic architecture. In the Azerbaijan area due to the mountainous climatic conditions, the architecture features of Iranian mosques such as porch and central courtyard are less observed. And the central courtyard in this climate is converted in harem (shabestan) through covering the ceiling and using column (Omrani, 2007: 18).  
In the Ilkhanid and Timurid era the element of column was applied in stony form with moqarnas capitals in the mosques of Azerbaijan. By the beginning of Safavid era, we observe changing the material of column and capital from stone to wood in the mosques. In this period, the procedure of using column was maximized and in the following affected on the columns and capitals of Safavid palaces as well as the buildings of Qajar era, particularly in the bathrooms and mosques. This article studies the background and evolution of applying column and its function in the architecture of Azerbaijan and the role that played in the architecture of the columned palaces of Safavid era. 

Review and Analysis 
The main element in the columned buildings to construct column and ceiling coverage is wood. Probably one of the reasons that in the early centuries of Islam the normal form of dome and porch becomes the most common architecture method is lack of wooden resources in some regions (Ukan, 2002: 203). But in Azerbaijan due to the suitable environmental conditions for growth of trees and availability of them, the columned architecture continues its life more or less during the medieval Islamic centuries. Entering the Ilkhani era and transferring centrality to Azerbaijan, the old procedure of columned architecture appeared again and was represented in the local mosques of Asnagh and Jamalabad and then became the architecture pattern of mosques of Safavid era in Azerbaijan and columned palaces of this era. 
The most important feature of Asnagh and Jamalabad mosques is stony walls and columns and using timber to cover ceiling and also the decorations of capitals and columns that continues to exist in Safavid era in the columned mosques of Maragheh, Bonab and columned palaces of this era. The height of the stony columns of these mosques is consistent completely with the height tendency of Azeri style of Ilkhanid era. The stony columns of Mollarostam and Sheykhbaba mosques that are related to the Timurid era are the climax of the art of column carving. They are implemented by the same procedure of Asnagh and Jamalabad mosques with the difference that inscriptions have been made on the columns body. Given the remaining of these columns it seems that in the Timurid era, construction of columned buildings was in Ilkhanid method with the same materials. 
In Safavid era due to developing many buildings and acceleration in architecture, the stony columns were substituted by wooden columns with the same dimension and decorations in order to speed up the construction of buildings. In this era the high wooden columns were put on the stony plinths. The capitals were made from timber and moqarnases were decorated by inscription and painting. 
Among the most famous wooden-columned mosques of the early Safavid era affected by Ilkhanid and Timurid stony-columned mosques are: Mollarostam, sheykhbaba, Rihan, sheykhtaj, Zarir, Mehrabad, Zargaran, Ajabshir etc. among the most important decorative features of these mosques can refer to the moqarnas decorations and paintings on the plinths, high wooden narrow columns, stony plinths as well as the painted wooden ceilings that in the continuation of their evolution process effect on Safavid palaces of Isfahan including Chehel Sotoon and Ali Ghapoo palaces and other columned buildings of this era. 

Conclusion
Column in architecture is used mostly in the regions in which the resources of wood and stone are available sufficiently. Azerbaijan is among these regions. Existence of sufficient wood and stone resources has resulted in construction of columned mosques in this region of which most prominent examples are Asnagh and Jamalabad mosques. The columns of these mosques represent the peak of column carving in the Islamic era. How these mosques are constructed and ceiled affected on the architecture of the next periods throughout Iran, such that a close similarity is observed in the columns of these mosques with the Safavid and Qajar era. Further, it can be concluded that construction of Safavid columned palaces somehow complement Ilkhani columned architecture that was represented in Asnagh and Jamalabad mosques and after its evolution period in Safavid wooden mosques of era was utilized in the construction of palaces.