The Persian domes of different historical periods are distinguished by their transition levels: plumes or brackets that mark the transition from supporting structures to the circular base of a dome. The drums, after the khanate era, tend to be very similar and have an average height of 30 to 35 meters aboveground. They are found where windows are opened. The inner shells are commonly semicircular, semi-elliptical, pointed, or saucer-shaped. The outer shell of a Persian dome is reduced in thickness every 25 or 30 degrees from the base. The outer shells can be semi-circular, semi-elliptical, pointed, conical, bulb-shaped, and this external shape is used to categorize them. The pointed domes can in turn be classified as having low, medium or a sharp and bulb profile. The double domes use internal reinforcements with wooden uprights between the shells, with the exception of those with external conical shells.
Persian architecture probably inherited an architectural tradition of building the dome from the early Mesopotamian domes. Because of the scarcity of wood in many areas of the Iranian plateau, domes were an important part of vernacular architecture during Persian history.
The remains of a large circular dome-shaped room 17 meters in diameter in the Parthian capital of Nisa may have been dated to the first century AD. It "shows the existence of a monumental dome tradition in Central Asia, which until then had been unknown and which seems to have preceded the Roman imperial monuments or at least grown independently of them." It is likely that it had a wooden dome.
The Temple of the Sun in Hatra seems to indicate a passage from halls to columns with an entablature architecture to the vaulted building and dome in the first century AD, at least in Mesopotamia. The domed hall of the temple shrine was preceded by a barrel vaulted Iwan, a combination that would later be used by the Sassanid Empire.
An example of a particular room of the domed building of 100 AD about is found in the city of Babylon in Life of Apollonius of Tyana Philostratus, The hall was used by the king to judge and was decorated with a blue stone mosaic to resemble the sky, with images of gods in gold.
A Pendentive bulb shape dome can be seen in the relief sculpture of the Arch of Septimius Severus in Rome, its shape apparently derived from the use of a square curtain as a reference.
The Persian invention of the plume, a series of concentric arches that form a half-cone above the corner of a room, enable the passage from the walls of a square room with an octagonal base to a dome. Previous transitions from a dome to a square room existed but remain precarious in quality and only attempted on a small scale, they were not reliable enough for large buildings. The domes with plume have allowed them to be widely used and have been brought to the forefront of Persian architecture later. The ruins of the Palace of Ardashir and Ghal'eh Dokhtar in the Fars region, Iran, built by Ardashir I (224-240) of the Sasanian Empire, are the first known examples.
The three domes of the Palace of Ardashir measure 45 feet in diameter and vertically elliptical, each with a central opening or eye that makes light penetrate. These buildings were built with local stone and mortar and covered with plaster on the inside. The large brick dome of the Sarvestan Palace, also in the Fars, but of a later date, shows more elaborate decorations and four windows among the angular pendentives. Also called "the Temple of Anahita", the building may have been a temple of fire. Instead of using a central eye on each dome, at the Palace of Ardashir and showing a bas-relief found at Kuyunjik, lighting was provided by a plurality of hollow terracotta cylinders inserted into the domes at regular intervals. More texts in Arabic, Byzantine and Western medieval sources describe a domed structure of the palace above the throne of Khosrow I decorated in blue and gold. The dome was covered with depictions of the sun, moon, stars, planets, the zodiac, and kings, including Khosrow I himself. According to Ado of Vienne and others, the dome could produce rain, and can be rotated with a thunder sound by means of horse-drawn ropes in a basement. The caravanserais surmount domes from the Sassanid period to the Qajar dynasty
br>Chahar-Taqi, or "Four Arches", are small structures of a small Zoroastrian temple of fire with four supports arranged in a square, connected by four arches, and covered by central ovoid domes. The Zoroastrian Niasar temple at Kashan and the Chahar-Taqi at Darrehshahr are the remarkable examples. These temples, with square domed buildings and entrances on the boards inspired by the forms of the first mosques after the Islamic conquest of the empire in the seventh century. These domes are the most numerous surviving type from the Sassanid period, some of which converted into mosques. Isolated domed chambers later called "mosque kiosk" may have developed from this. The pre-Islamic domes in Persia are commonly semi-elliptic, with pointed domes and those with conical outer shells being most of the domes of Islamic periods.
lthough the Sassanid did not create monumental tombs, the Chahar-Taqi dome may have served as a memorial. A fragment of Sogdia painting from the early 8th century found in Panjakent seems to represent a funerary dome (perhaps a tent) and this, along with some architectural ossuaries, indicate a possible tradition in Central Asia of a funerary dome-shaped association. The area of northeastern Iran (along with Egypt) was one of two important areas for early developments of Islamic domed mausoleums, which appear in the tenth century.
The first Islamic domes known in Persia, such as that of the Great Mosque of Qom (878) and the tomb of Muhammed b. Musa (976), seem to have continued the rounded form the Sassanid. The domed mausoleums have contributed greatly to the development and spread of the dome in Persia at the beginning of the Islamic period. From the tenth century, the domed tombs were built for Abbasid caliphs and Shiite martyrs. The pilgrimage to these sites may have contributed to spreading its form. The first surviving example, the Qubbat-al Sulaibiya, was an octagonal structure with a central dome on a drum built around 892 in Samarra. These domes with pavilions are known from Shiraz to Bukhara in the tenth century. The Samanid Mausoleum in Transoxiana dates back to later by 943 and is the first to have plumes that create a regular octagon as the base for the dome, which later became the practice.
The Arab-Ata Mausoleum, also in Transoxiana, can be dated to 977-78 and uses Muqarnas among the pendentives for a more uniform transition to the dome. Flat towers for cylindrical or polygonal tombs with conical roofs on the domes exist from the eleventh century. The first example is the Gonbad-e Qabus tower tomb, 57 meters high, which extends for 9.7 meters, and was built in 1007.
The Turkish Seljuks built tower tombs, called "Turkish triangles", as well as cube-covered mausoleums with a variety of dome shapes. Seljuk domes including conical, semicircular and pointed-shaped with one or two shells. As well as the superficial semicircular domes are mainly found in the Seljuk period. The double-shell domes were either discontinuous or continuous. The double-shelled domes were separated from each other by an angle of 22.5 degrees from their base, like the dome of the Friday mosque of Ardestan, while the discontinuous domes were completely separated, like those of the towers tombs Kharraqan. This pair of 11th-century brick tower tombs in Kharraqan in Iran are the oldest known examples of double-shelled brickwork. The domes may have been erected on the wooden model of previous double-shell domes, such as that of the Dome of the Rock. It is also possible, because the upper portions of both outer casings are missing, that a part of the outer domes may have been made of wood. These brick domes of the mausoleum were built without the use of centering, a technique developed in Persia
IAfter the destructive effects of the different Mongol invasions, Persian architecture flourished again in the times of the Ilkhanato and Timuride. The characteristic of these domes are the use of high drums and different types of double discontinuous shells, and the development of triple shells and internal reinforcements. Starting from Ilkhanate, the Persian domes reached their final configuration of the structural supports, transition zones, the drum, and the shells, and the subsequent evolution was restricted to variations in shape and geometry. The construction of the tomb towers diminishes
The tower tombs of this period, such as the tomb of Abdas-Samad Esfahani in Natanz, sometimes have domes with muqarnas, although usually they are plaster shells that hide the underlying structures. The high proportions of the Friday Mosque of Varamin are mainly due to the greater height of the transition zone, with the addition of a section of sixteen sides above the main area of the muqarnas plumes. The 7.5 meter wide double dome of the mausoleum Soltan Bakht Agha (1351-1352) is the first known example in which the two dome shells have very different profiles, which spread rapidly throughout the region. The inner and outer shells had radial reinforcements joined together. A first example of a dome chamber almost completely covered with decorative tiles is that of the Friday Mosque of Yazd (1364), as well as the many of the Shah-i-Zinda mausoleums in Samarkand. The development of the high drums continued also during the timurid period.
In the Timurid capital of Samarkand, nobles and rulers in the fourteenth and fifteenth centuries began the construction of tombs with double-shell domes containing cylindrical drums masonry between the shells. In the Gur-e Amir, built by Timur around 1404, a wooden structure on the inner dome supports the outer bulb dome. Radial tie rods at the base of the bulb dome provide additional structural support. The wooden reinforcement rings and the stone rings connected by iron cramps were also used to compensate for the structural problems introduced by using these drums. Radial sections of brick walls with wooden struts were used between the discontinuous shells of the double domes to provide structural stability in the late 14th century.
A miniature painted in Samarkand shows that bulb domes have been used to cover small wooden pavilions in Persia by the early 15th century and have gradually gained popularity. The large, high-grooved domes characteristic of the 15th century timurid architecture were the culmination of the Central Asian and Iranian tradition of tall domes with blue glazed tile claddings and other colors. The Mausoleum of Khoja Ahmed Yasawi, located in southern Kazakhstan has never been completed, but has the largest existing brick dome in Central Asia measuring 18.2 meters in diameter. The exterior of the dome is covered with green glazed hexagonal tiles with gold patterns.
he mausoleums were rarely built as separate structures after the fourteenth century, but were often attached to madrasa in pairs. The domes of these madrasas, like those of the madrasa of Goharshad (1417-1433) and the madrasa of Ḵargerd (1436-1443), have incredibly innovative interiors. They used twisted bows to support a narrow inner dome from the lower floor, a change that may have originated with the use of the fourteenth century of small lantern domes above the transverse vault. The madrasa of Goharshad is also the first dome with a triple shell. The central dome may have been added as a reinforcement. Triple shell domes are rare outside the timurid period. The dome of the Amir Chakhmaq mosque (1437) has a semi-circular inner shell and an advanced system of reinforcements and wooden struts supporting a superficial pointed outer shell. In particular, the dome has a circular drum with two levels. Another double dome dome of the Seljuk period at the Bayazid Bastami Shrine complex was changed during the Timurid period with the addition of a third conical cap on the current two domed shells.
The Uzbek architecture of the region around the Transoxiana has kept the timurid style of the domes of the buildings. Where the domed chambers were surrounded by ivan axial and octagonal corner chambers, as at the Khwaja Abu Nasr Parsa sanctuary (circa 1598), which provided a model for Indian mausoleums such as Humayun's Tomb in Delhi or the Taj Mahal. Some of the ancient domed survivors, called tīmcās, can be found from the Shaybanids era in Bukhara..
The domes of the Safavid dynasty (1501-1732) are characterized by a distinctive round profile and are considered the latest generation of Persian domes. They are generally thinner than the previous domes and are decorated with a variety of colored glazed tiles and complex plant motifs. The dome of the Blue Mosque of Tabriz (1465) has the interior covered with "dark blue with hexagonal tiles and gilding". Ali Qapu's palace in Isfahan includes small domed chambers decorated with artificial vegetation.