Iran has a rich and varied architectural history going back over 3,000 years, and the remains of Iranian architectural monuments can be found from Syria to India and China. Iranian architecture make uses of a great variety of techniques such as stone carving, stucco and plasterwork, tile and brickwork, mirror and glasswork, and other ornamental elements. As in any architecture, geographical, religious, political, technological, and natural factors determine the quality and quantity of architecture. Many of the diverse architectural designs and structures in Iranian lands resulted from the availability of suitable natural resources and consideration of factors such as climate. The landscape itself is a source of both constraint and freedom. The Iranian kavir (desert) imposed enormous limitations on the structural designs and the kind of buildings Iranian architects could produce. However, the challenge of working with the vast tracts of desert land has offered Iranian architects the chance to be creative with both their designs and responses to societal needs. Another important variable shaping architectural characteristics is the technological knowledge and skills available in the region. Some good examples of responses to these technological and environmental challengse are the Iranian bâdgirs (wind-catcher towers), qanâts (underground water channels), and âb-anbârs (water reservoirs). Since much of Iran is desert, Iranian cities and towns were confronted with the challenge of dealing with water shortages, high levels of heat, and at times strong winds. Given the limited resources available to builders in these towns, building materials consisted mainly of mud and its derivatives. Mud and mortar excavated from construction sites are often used for buildings, thus creating a modicum of self-suffi ciency. Baked or unbaked bricks and mud effectively resist the incessant rays of the sun in the hot summer months. During the cold season, little heat is used for warming the interiors because hardened, unbaked brick walls act as good insulation. Buildings are often constructed with tall walls, arched roofs, water reservoirs with arched domes, and air traps or wind catchers. Residential structures often are positioned at a specific angle to collect maximum heat and allow for winds to bring cooler air into the structure. The bâdgir (“wind-catcher tower”) was an architectural innovation to capture cool air in a desert environment. These towers were set at a specific height on the roof of a building to capture a breeze and transfer it underground within the structure in order to bring cool air into large rooms and halls in the hot days of the season. Bâdgirs served as ventilators using wind energy to operate. They were placed on a part of the structure where they could collect maximum air fl ow. Ducts were located at the four corners to capture the wind from any direction. When capturing wind from one direction, ducts in the other three directions would be closed. Some bâdgirs had an arched roof that absorbed heat from the strong sunshine during the day and radiated it back more quickly at night. In this way, bâdgirs worked as simple air conditioners in arid and dry regions. In some houses, a water reservoir was built underground, and the air from the bâdgir was routed to it to cool the water in the reservoir. The impact from the airfl ow would also stir the water and prevent stagnation. Another necessity of desert living was controlling water distribution in very high temperatures. Iranians were among the first to construct underground water systems. They also constructed dams, canals, bridges, and means for adequately distributing the water to both residential and agricultural areas. A number of these dams, bridges, and water canals from earlier times are still found in Iran. The city of Isfahan has the most magnificent bridges built over the Zâyandeh Rud, a river dividing the city into south and north, with 12 bridges from the Sasanid through Safavid periods crossing it. The oldest of these bridges is the Shahrestân from the Sasanid period. The Allâhverdi Khân bridge is a 1181-foot long, 46-foot wide bridge with 33 spans built in a.d. 1602 The Khâju Bridge, in two stories and with a 438-foot length and 40-foot width, is a dual-function structure built during the reign of Shah ‘Abbâs II (1642–1666) in order to serve as both a bridge and a dam. Wide and thick timbers were used to change its function from one to the other. The second fl oor of the bridge included fantastic pavilions decorated with stucco carvings and inscriptions. The main parlor was often used for royal receptions and national festivals. Underground water reservoirs, called âb-anbârs, were used (occasionally in conjunction with a bâdgir) to help cool water. These reservoirs were built deep underground and often covered by a domelike roof with a few ducts. Water was transferred from qanâts and used for various purposes in the house. The city of Yazd, located in the middle of the Iranian desert, is known to have hundreds of these âb-anbârs. Another structure used in conjunction with water reservoirs was the traditional icehouse ( yakhchâl ). The icehouse took advantage of cold temperatures at night temperature or in winter to transform water into ice. The icehouse was typically a big pit about 35–50 feet deep along with several shallow rectangular water lagoons. Walls of different heights were built around the lagoons to allow for freezing and to keep out the sunlight. Once the ice was formed, it was cut into manageable pieces and transferred to the underground storage place. Aside from environmental and technological factors infl uencing the relationships between people, environmental resources, and various forms of constructions, sociological variables affected Iranian architecture. Many distinctive features of Iranian architecture are determined by cultural variables, including a desire for security, religious considerations, and attitudes towards private and public life. The distinct qualities of Iranian architecture separate it from arts produced by culturally different people in the same territorial environment. Certain design elements have persisted throughout the history of Iranian architecture: extensive decorations, the high-arched portal set within a recess, columns with bracket capitals, columned porches ( tâlârs ), domes on arches, networked courts, interior courts with a pool, and tall towers. Three elements defi ned the archetypal traditional Iranian house: energy, space, and boundary. Energy determined the utilization of various units of space (a room or special hall) at different times for generating fl ow and interaction. The space in these houses was fl exibly defi ned and could be redefined to suit new needs. The boundary established the relationships between people inside the house and protected them against the outside world. The space connected different units of the interior. Given the numerous attacks on Iran in the course of history, and the existence of nomadic populations moving around all the time, even cities felt insecure to leave themselves exposed. Many cities had a large surrounding wall, thus turning these cities into fortifi ed communities. The best example is the city walls of Yazd, which historically has served as a shelter for Persian imperial dynasties holding out against the Arab, Saljuq, Mongol, Timurid, Safavid, and Afghan invasions of Iran. Religious life also has been a main inspiration behind much of Iranian architecture throughout its history. The Zoroastrian emphasis on light as a source of beauty and clarity continued to exert influence even in the Islamic period. The Arab invasion in the seventh century and Islamic culture influenced Iranian architecture and gradually affected the native structures. Islam limits interactions between men and women who are not related to each other and demands much more privacy from women than other religions. This restriction has had an impact on Iranian architectural design, city planning, and housing plans. Since families had to keep female members out of public view, Iranian houses are all walled and not easily accessible to passersby. The internal dispositions of houses convey a sense of being more inward looking. From an architectural perspective, most buildings in the more traditional cities like Yazd and Natanz represent a form of contained and closed space. What separates a house from the outside is a wooden, or today metal, door lacking any glass or see-through material. The door secures the inside from the outside. This inward-looking attitude has also affected the exterior of housing, especially prior to modern housing in the twentieth century. The exterior architectural design does not reflect the sophistication and craftsmanship applied to the interior. The quality of artwork on the door and its entrance were the only visible markers of social class observable from the outside. Much of the artwork and design are visible in the interior and the courtyard ( hayât ). The hayât is an important buffer zone separating the interior space from the outside world and also providing resources not deemed appropriate in the interior. These resources included water and washing facilities, which traditionally were often kept on the opposite side of rooms in the yard. At the center of hayât, there was always a small pool called howz, surrounded with fl owers, grape vines, and trees, especially pomegranates and fi gs. The hayât also served as a transitional stage for entering or departing the house. Rooms never opened directly onto the street or public arena—a phenomenon rarely observed in current apartment buildings. Houses had a small enclosed transitional space called hashti, which itself directed into a hallway ( dâlân vorudi ). The internal space was set up to accommodate different daily and nightly activities, gender relationships, various religious and cultural rituals, and functional situations. Balance, symmetry, harmony, symbolism, and rhymes were important elements of interior design in the housing structures. Rooms were designed in such a way that they would angle toward Mecca, the direction Muslims face when praying. The interior of houses were also subject to cultural variables such as status hierarchy and a collectivist culture, which did not allow for much privacy. Traditional homes of the affl uent contained rooms that often opened to each other and did not allow for the kind of privacy found in modern Western housing. The infl uence of this collectivist attitude is also found in the act of building itself. Construction of housing in rural areas has been a communal effort that enhances the community’s solidarity. Two other factors have played a decisive role in the development of architecture in different periods of Iranian history. Depending on their social, political, religious, and financial status, patrons made special demands refl ecting their priorities. Religious patrons demanded religious motifs; the political elite were more interested in motifs of grandeur; some female patrons showed interest in refl ecting women’s concerns in both the decorative arts and structural designs. Religious endowments and charities led to the construction of mosques, mausoleums, cemeteries, religious halls ( takiyeh ), cisterns ( âb-anbâr), and other public facilities. By their nature and support, these resources contributed to the cohesive structure of communities ( mahaleh ) within the city. Another factor contributing to the cohesiveness of these communities was their functional separation. Traditional Iranian cities separated residential quarters from commercial centers (bazaar and caravansaries) and public squares ( maydân s). Religious and often ethnic minorities each lived in their own quarters. These quarters were named accordingly (such as mahalehe tork-hâ, meaning“Turkish neighborhood” or mahaleh-e arâmaneh , meaning “Armenian neighborhood”). All cities contained a bazaar, a grand mosque ( masjed-e jâme‘ ), and a citadel ( arg ). Traditional cities did not divide along class lines. Rich and poor were mixed in traditional neighborhoods. The separation of affluent neighborhoods from slums in the city, the north-south divide, and other economic divisions are all products of modernization and the introduction of Western economic relationships. The bazaar, as the center of commercial and civic life, was a key feature of urban life in Iran and the Islamic world in general. Bazaars were built in the heart of the city and housed many public facilities such as mosques, baths, and caravanserais for both city dwellers as well as tourists. Major cities like Tehran, Isfahan, Shiraz, Tabriz, Yazd, and Mashhad have well-known and frequently visited bazaars. Smaller towns also have bazaars as the center of economic activities. The architectural design of these bazaars was no simple matter as most were domed and covered large expanses of shops and other public facilities. Finally, it should be noted that aside from the recent Western influence on Iranian architecture (to be discussed later in this chapter), even traditional architecture has been influenced by foreign styles, either those of neighboring countries or of those of peoples that invaded and dominated Iranian society. Iranian builders and designers, though maintaining their cultural and national identity, often looked outside of their borders to enhance the horizon, scope, and richness of their work. However, Iranian architecture often absorbed those foreign elements while remaining true to its originality and beauty. Though influenced by Arab, Mongol, Turkish, Chinese, and central Asian cultures, the unique architectural style developed in Iranian society is the result of thousands of years of work by master artists and architects who were inspired by faith, national pride, and original creativity. To have a better understanding of the diversity and richness of Iranian architecture, it is appropriate to describe its evolution during distinct historical periods. For the purpose of this chapter, we will present Iranian architecture in three periods: pre-Islamic (to the seventh century a.d. ), Islamic (to the end of the nineteenth century), and contemporary (twentieth century). What follows is not a comprehensive survey of building and construction styles but a brief description of architectural developments across the wide region historically known as Iran. It should be mentioned that much of what is being described concerns settled life, not that of the nomads who were also a part of this stretch of land and found among ethnically diverse groups and lifestyles. Nomadic abodes were varied and often depended on the ecological system in which nomads lived. Available resources for nomadic constructions were often few, and the nomadic life style did not allow for accumulation of many goods and permanent settlement. Materials produced for constructing their tents were easy to pack, yet delicate and full of decorative elements, demonstrating a creative and self-generative culture.