Persian domes or Iranian domes have an ancient origin and a history extending to the modern era. The use of domes in ancient Mesopotamia was carried forward through a succession of empires in the Greater Iran region.
An ancient tradition of royal audience tents representing the heavens was translated into monumental stone and brick domes due to the invention of the squinch, a reliable method of supporting the circular base of a heavy dome upon the walls of a square chamber. Domes were built as part of royal palaces, castles, caravansaries, and temples, among other structures.
With the introduction of Islam in the 7th century, mosque and mausoleum architecture also adopted and developed these forms. Structural innovations included pointed domes, drums, conical roofs, double and triple shells, and the use of muqarnas and bulbous forms. Decorative brick patterning, interlaced ribs, painted plaster, and colorful tiled mosaics were used to decorate the exterior as well as the interior surfaces.
Characteristics
Persian architecture likely inherited an architectural tradition of dome-building dating back to the earliest Mesopotamian domes. In Central Asia, mudbrick domes have been documented as far back as the late third millennium BC. Buildings with domes made of un-fired bricks have been found at fourth century BC sites at Balandy 2 and Koj Krylgan kala in Khorezm. Due to the scarcity of wood in many areas of the Iranian plateau, domes were an important part of vernacular architecture throughout Persian history.
Persian dome chambers in mosques were derived from the chahar taq dome chambers of Sasanian Fire Temples and consisted of three parts: the load-bearing system, the transition tier, and the dome itself. Double and triple shell domes had considerable space between the shells or could be connected and the outer shell could be conical, onion-shaped, or bulbous, with bulbous shaped domes being the last and most influential development. The transition tiers used squinches or pendentives, and beginning in the Timurid period the curved surface was divided by a pattern of intersecting arches called an "arch net", or rasmi sazi, which had its culmination in the Safavid period.
Persian domes from different historical eras can be distinguished by their transition tiers: the squinches, spandrels, or brackets that transition from the supporting structures to the circular base of a dome. Drums, after the Ilkanate era, tend to be very similar and have an average height of 30 to 35 meters from the ground. They are where windows are located. Inner shells are commonly semi-circular, semi-elliptical, pointed, or saucer shaped. The outer shell of a Persian dome reduces in thickness every 25 or 30 degrees from the base. Outer shells can be semi-circular, semi-elliptical, pointed, conical, or bulbous, and this outer shape is used to categorize them. Pointed domes can be sub-categorized as having shallow, medium, and sharp profiles, and bulbous domes as either shallow or sharp. Double domes use internal stiffeners with wooden struts between the shells, with the exception of those with conical outer shells.
Persian mathemetician Abul Wafa al-Buzjani (940–998) was the first to "study the geometric constructions of ornamental patterns and the projection of these patterns onto a sphere in his treatise The book on what the artisan requires of geometric constructions (Kitab fima yahtaju ilayhi al-sani' min a'mal al-handasa)." He used two-dimensional drawings to illustrate how to tile a sphere using various polygons in a tessellated pattern.
Elamite Era In 2007, during excavation and construction activities near the village of Jubaji in Ramhormoz County, Khuzestan Province, a royal tomb dating back to the 6th century BCE was discovered. The structure consists of an underground stone burial chamber oriented east–west, measuring 4.5 meters in length and 2.2 meters in width, which is accessible via a staircase on the western side. It is likely that a dome once covered this space. Tombs with similar dome (and vault) structures, dating from the 8th to the 6th centuries BCE, have also been found in Apadana at Susa.
Achaemenid Empire
Although they had palaces of brick and stone, the kings of Achaemenid Persia held audiences and festivals in domical tents derived from the nomadic traditions of central Asia. They were likely similar to the later tents of the Mongol Khans. Called "Heavens", these tents emphasized the cosmic significance of the divine ruler. They were adopted by Alexander the Great after his conquest of the empire, and the domed baldachin of Roman and Byzantine practice was presumably inspired by this association.
Parthian Empire
The remains of a large domed circular hall measuring 17 meters in diameter in the Parthian capital city of Nyssa has been dated to perhaps the first century AD. It "shows the existence of a monumental domical tradition in Central Asia that had hitherto been unknown and which seems to have preceded Roman Imperial monuments or at least to have grown independently from them." It likely had a wooden dome. The room "contained a portrait of Mithradates II and, along with other structures at the site, hosted some sort of cult activities connected to the memory of the kings of kings."
The Sun Temple at Hatra appears to indicate a transition from columned halls with trabeated roofing to vaulted and domed construction in the first century AD, at least in Mesopotamia. The domed sanctuary hall of the temple was preceded by a barrel vaulted iwan, a combination that would be used by the subsequent Persian Sasanian Empire.
A bulbous Parthian dome can be seen in the relief sculpture of the Arch of Septimius Severus in Rome, its shape apparently due to the use of a light tent-like framework.
An account of a Parthian domed palace hall from around 100 AD in the city of Babylon can be found in the Life of Apollonius of Tyana by Philostratus. The hall was used by the king for passing judgments and was decorated with a mosaic of blue stone to resemble the sky, with images of gods in gold. It may have been an audience tent; Philostratus described the ceiling as "constructed in the form of a dome like the heavens."
Sasanian Empire
Caravansaries used the domed bay from the Sasanian period to the Qajar dynasty. The Persian invention of the squinch, a series of concentric arches forming a half-cone over the corner of a room, enabled the transition from the walls of a square chamber to an octagonal base for a dome. Previous transitions to a dome from a square chamber existed but were makeshift in quality and only attempted on a small scale, not being reliable enough for large constructions. The squinch enabled domes to be widely used and they moved to the forefront of Persian architecture as a result. The domes supported on squinches had a circular horizontal section and a half-elliptical vertical profile made without centring.
The ruins of the Palace of Ardashir and Ghal'eh Dokhtar in Fars province, Iran, built by Ardashir I (224–240) of the Sasanian Empire, have the earliest known examples of squinches. The three domes of the Palace of Ardashir are in diameter and vertically elliptical, each with a central opening or oculus to admit light. They were built with local stone and mortar and covered with plaster on the interior. The dome and the squinches were made of "cobbles embedded in gypsum mortar".
At the center of the palace of Shahpur, at Bishapur, there is a vertically-elliptical dome that rests directly on the ground and is dated to 260.
The large brick dome of the Sarvestan Palace, also in Fars but later in date, shows more elaborate decoration and four windows between the corner squinches. Also called "the Temple of Anahita", the building may have been a Fire temple. The squinches of the 5th century Sarvestan Palace dome were in the form of half-pavilion vaults, rather than conical squinches. Although the dome was made with brick, the squinches were made with rough stone and cobbles in gypsum mortar. Instead of using a central oculus in each dome, as at the Palace of Ardashir and as shown in the bas relief found at Kuyunjik, lighting was provided by a number of hollow terracotta cylinders set into the domes at regular intervals.
Multiple written accounts from Arabic, Byzantine, and Western medieval sources describe a palace domed structure over the throne of Chosroes decorated in blue and gold. The dome was covered with depictions of the sun, moon, stars, planets, the zodiac, astrapai, and kings, including Chosroes himself. According to Ado and others, the dome could produce rain, and could be rotated with a sound like thunder by means of ropes pulled by horses in a basement. The castle of Qasr-e Shirin had a domed chamber at the end of a long barrel-vaulted iwan. The late-Sasanian Tāq-i Kasrā in Ctesiphon may also have led to a domed throne room.
Chahar-taqi, or "four vaults", were smaller Zoroastrian fire temple structures with four supports arranged in a square, connected by four arches, and covered by central ovoid domes. The Niasar Zoroastrian temple in Kashan and the chahar-taqi in Darreh Shahr are examples. They are numerous throughout the province of Pars, possibly starting from the early Sasanian empire, and are known to be part of the palatial architecture of Ardashir I. Such temples, square domed buildings with entrances at the axes, inspired the forms of early mosques after the Islamic conquest of the empire in the 7th century. These domes are the most numerous surviving type from the Sasanian period, with some having been converted into mosques. The later isolated dome chambers called the "kiosk mosque" type may have developed from this. Pre-Islamic domes in Persia are commonly semi-elliptical, with pointed domes and those with conical outer shells being the majority of the domes in the Islamic periods.
Although the Sasanians did not create monumental tombs, the domed chahar-taqi may have served as memorials. A Soghdian painting fragment from the early eighth century found at Panjakent appears to depict a funerary dome (possibly a tent) and this, along with a few ossuaries of an architectural nature, indicates a possible tradition in central Asia of a funerary association with the domed form. The area of north-eastern Iran was, along with Egypt, one of two areas notable for early developments in Islamic domed mausoleums, which appear in the tenth century.
Early Islamic period
The earliest known Islamic domes in Persia, such as the Great Mosque of Qom (878) and the tomb of Muhammed b. Musa (976), seem to have continued the rounded Sasanian form.
Domed mausoleums contributed greatly to the development and spread of the dome in Persia early in the Islamic period. By the 10th century, domed tombs had been built for Abbasid caliphs and Shiite martyrs. Pilgrimage to these sites may have helped to spread the form. The earliest surviving example in Islamic architecture, the , was an octagonal structure with a central dome on a drum built around 892 in Samarra on the Tigris. The mausoleum of Ali in Najaf, built by the Hamdanid governor of Mosul before 930, had a high dome supported by columns and had entrances on all sides. Reportedly, Buyid dynasty kings built high domes over their tombs and the tombs of minor princes had lower domes.