Dome is a structural element in architecture that has changed its shape, functions, and materials from time to time representing the advancement of human beings in mathematics and technology. The shape of it is the half of a hollow sphere, mainly placed on the roof or as a whole it serves as a shelter. Dome-shaped structures do have many advantages like energy-efficient (easy to heat and cool the interior), strong and durable, weatherproof, and easy to maintain. Here’s how it evolved:
Early and indigenous domes
Dome structure acted as shelter from prehistoric times when humans used local materials to build it. The local material varied from place to place and thus the shelter structure varied and also the methods of construction.
In Mezhirich, Ukraine, 4 huts and 139 mammoth bones were found which dated 19,280 – 11,700 BC. This is the earliest evidence of a dome-shaped shelter.
The Thule people of the Canadian Arctic region used whalebone frames to build a parabolic dome-shaped structure during 1300 AD. Inuit people and Eskimo built an igloo with snow, which was also known as a snow hut.
People in Europe, Asia, and Africa used to make a dome-shaped shelter with loam, mud bricks, or adobes. In the ancient Near East, poorer people built around the planned house with small domes with corbelled stone or brick. In this period it didn’t have any role in monumental structures. In the Ancient Middle East and the Mediterranean, this structure was used as granaries, Mastaba tombs, tents, and treasuries.
This structure existed from the times of Mesopotamia and it evolved till the modern ages. These are characterized for their transition tiers: the squinches, spandrels, or brackets which support the circular dome. The inner shells of it are semi-circular, semi-elliptical, pointed, or saucer-shaped and the outer shell is semi-circular, semi-elliptical, pointed, conical, or bulbous. The evolution of Persian domes can be subcategorized in the period of Pre-Islamic and Islamic periods.
These were inherited from Mesopotamian dome buildings which were made up of un-fired mud bricks. In the period of the Achaemenid Empire, dome-shaped tents were used for organizing special occasions. In the Parthian Empire, wooden domes came into the act and large ones were made for halls and palaces. The Bulbous Parthian dome can be found in the Arch of Septimius Severus in Rome.
In the period of the Sasanian Empire, the ruins of the Palace of Ardashir and Ghal’eh Dokhtar in Fars Province, Iran (224–240) are the earliest known example of squinches. The domes are built of local stone and mortar and covered with plaster on the interior.
The tomb of Muhammed b. Musa and the Great Mosque of Qom, are the buildings of the Early Islamic period which shows a few characteristics of Sasanian dome form. The Samanid Mausoleum in Transoxiana is the first building to have a regular octagon base squinch which became a regular practice of dome building.
Shallow semi-circular and double-shell domes introduced on Friday mosques were introduced. Wooden double-shell domes could be seen in Dome of the Rock. Jameh Mosque of Qazvin is one of the largest domes with a span of 15.2 meters, built in the period of the Seljuq dynasty.
After repeated Mongol invasions, Persian Architecture once again developed in Ilkhanate and Timurid periods. The domes in the period had high drums with a double shell to triple shell structure. Timber reinforcement rings and rings of stone linked by iron cramps are used to build a bulbous dome in the Timurid period.
Bulbous profile domes are greatly developed and interiors are improved in the Safavid dynasty. They became thinner and colored glazed tiles and complex vegetal patterns came up in the interior of the domes. Shah Mosque and the Mādar-e Šāh madrasa, the exterior of them are decorated with light blue glazed tile. The dome of Shah Mosque is a discontinuous double-shell 33 meters wide and 52 meters high.
Roman and Byzantine domes
Rounded arches, vaults, and dome structures and the use of concrete and bricks are the main characteristics of Roman architecture. The use of concrete and bricks helped Romans to build large-scale domes of high strength and durability. Romans used domes in baths, villas, palaces, and tombs with Oculi being a common feature. The types of domes that are commonly found are shallow saucers, segmental, and ribbed. The Roman domes evolved from Greek to Byzantine and then it influenced the world and it evolved region-wise.
In the Early Imperial Period, the domes were used over hot baths so to maintain the heat of the environment. The use of them was not that much before the 1st century AD but during the Roman Imperial period, they were used in many buildings as it is used in monumental scale. The first Roman large dome dates back to the age of Augustus (27 BC – 14 AD) which had a span of 21.5 meters (71 ft).
Under Emperor Nero and the Flavians in the 1st century AD to 2nd century AD, the use of domes in buildings increased tremendously. The buildings like Domus Transitoria, Domus Aurea, or “Golden House”, Santa Maria Della Rotonda, etc came up in their period.
The Pantheon in Rome is the most famous Roman monument having the largest dome with a span of 43.4 meters (142 ft) was completed by Emperor Hadrian as part of the Baths of Agrippa. This is the first time when the dome has coffering’s in the interior of it which made it more decorative and lighter in weight. During the 2nd century AD, some of the largest domes of the temple were also constructed like in the Temple of Venus, Temple of Diana, and Temple of Apollo.
With the advancement of mathematics and the development of construction technology, the Temple of Minerva Medica, used brick ribs and step-rings of pumice aggregate concrete to form a decagonal dome. During the 4th century AD, under Empire Constantine, many buildings were built and some baths were rebuilt with a large dome with the use of concrete and wood.
During the 6th century AD, the domed church architecture started coming up. During this time Hagia Sophia was built and rebuilt several times due to partial collapse for earthquakes. Now the central dome is about 750 mm thick, a span of 32 meters (105 ft) wide and it contains 40 radial ribs, which is placed between 40 windows in the base.
In the Middle of the Byzantine period, the domes became more geometrically complicated, higher in height, lighter in weight, more stable, and more decorated. Some of the well-known buildings like Hosios Loukas, Kalenderhane Mosque, Gül Mosque, Enez Fatih, and Pantokrator monastic complex. In later times, the dome architecture influenced a lot of regions of the world and it continued to evolve. In the age after Byzantine, the dome structure began to come up in cities like Venice, Southern Italy, and Sicily.
Once again in the Italian Renaissance, the construction of large domes was done for monumental structure. Architects like Filippo Brunelleschi, Donato Bramante, and Michelangelo started to build them with new methods of construction and mathematics.
The dome for Florence Cathedral in 1420, was built by Filippo Brunelleschi and Lorenzo Ghiberti. The dome is 42m wide and constructed of two shells. This still stands as the largest masonry-built dome. The domes of this period were mostly ribbed or spoked wheel designs.
The dome of St. Peter’s Basilica is another important dome modeled by Michelangelo, which began in construction in 1588. The dome is built with 16 ribs and an inner diameter of 42.7m.
The South Asian domes flourished with the start of Islamic rule in the region. These were built of stone, brick and mortar, and iron dowels and cramps. Tomb of Balban, is the earliest known half-dome of the region constructed in the 13th century AD. Gradually domes evolved and mostly used mosques and tombs. Alai Darwaza (1311), the tomb of Ghiyath al-Din Tughluq (1325), the tomb of Khan-i-Jahan Tilangani (1368, also the first octagonal tomb in Delhi) are few buildings with domes that are constructed.
In the Early Modern Period, in the Mughal Empire, lots of architects traveled from the Middle East and dome construction became more grandeur. These were made of a concrete shell with brick reinforcement. The buildings like Humayun’s tomb constructed by a Persian architect in 1562 and 1571 have domes with brick core and the central chamber is octagonal in plan and has a dome of 40m wide. The building also had Chatri, a domed kiosk on pillars which is also a characteristic of the Mughal roof. Then gradually buildings like the Taj Mahal in Agra, the tomb of Safdar Jang in Delhi, the tomb of Mohammed Adil Shah in Bijapur with a diameter of 41.15m are made in the Mughal period. After the Mughal period, these again flourished through Sikh architecture in the 18th century, which had ribbed with lotus design at the top and floral motifs at the bottom.
Modern period domes
In the Modern period, with the industrial revolution and the introduction of new materials, domes are used all over the world in various types of buildings and different styles. The size of it became wider than any other domes built previously. These were used in parliaments and capitol buildings, gasometers, observatories, libraries, churches, etc.
With the industrial revolution, the quality of materials enhanced and cost also decreased significantly due to mass productions. The domes started to be constructed using iron ribs. One of the earliest wrought iron domes of Kazan Cathedral was constructed by Andrey Voronikhin. An elliptical dome of span 66.9m by 56.5m is constructed at Royal Albert Hall in London by architect Henry Young Darracott Scott. Galleria Vittorio Emanuele II in Milan and the Galleria Umberto I in Naples are the two places that have a large glazed dome at the intersections over the covered shopping arcades. United States Capitol building and Old St. Louis County Courthouse are the buildings to be constructed with cast iron.
In the 20th century, the domes were constructed with a thin concrete shell. The dome of the Cathedral of St. John the Divine in New York City is the first example of modern shell construction in reinforced concrete. With time geodesic domes were used in radar enclosures, greenhouses, housing, and weather stations. Eden Project in the UK, Amundsen-Scott South Pole Station, U.S. Pavilion at Expo 67 in Montreal, Quebec, Canada are some of the examples of this construction.
With the invention of nylon, the tensile membrane structure came into dome construction. The buildings like the Millennium Dome in the UK, Georgia Dome are constructed with tensile membrane structures. With the advancement of motors, retractable domes are made over stadiums which open and close as required with motorized systems, Pittsburgh’s Civic Arena, Superdome of New Orleans, Montreal’s Olympic Stadium are some of the buildings having a retractable roof.
With lots of failure and trial and errors, human beings evolved the dome structure, every time they made and became successful and broke all the previous records. The structure is being modified day by day, and will evolve with contemporary materials and ideas and will address contemporary problems.