Dome of Soltaniyeh

On the way to Zanjan, a turquoise-colored dome shows itself as we pass by Soltaniyeh. The dome of Soltaniyeh is so well-colored and glazed that it is impossible to ignore the temptation of visiting it.

Soltaniyeh is a prominent example of Iranian architecture and is regarded as a key historical work in the development of Islamic architecture.

It is said to have been erected to be used as an eternal tomb of the 8th IL khan, Sultan Muhammad Khodabandeh or Al Jaito; however, no trace of his tomb has been found in the area, and this is still a mystery.

The Soltaniyeh Dome is also well-known worldwide and is the third-largest dome in the world after the Italian Church of Santa Maria and the Turkish Ayasufiye Mosque. It also holds the title of the largest historical dome in Iran and is listed on the UNESCO World Heritage site.

Is Soltaniyeh Dome the largest brick dome in the world?

When we search for Soltaniyeh’s name, in many sources we find the title of the world’s largest brick dome. This dome may have been the largest of its time, but it lost its title after the construction of the Florence Cathedral.

History of Soltaniyeh Dome

Before it became a city, Soltaniyeh was a vast plain used for hunting and recreation. Fourth Mongol Mughal Empire, Argun Khan, ordered the construction of Soltaniyeh city.

In the Ilkhanid period, Soltaniyeh was the third capital of the state after Maragheh and Tabriz. Sultan Mohammed Khodabandeh, also known as Oljaytu – the eighth Mongol sultan – also ordered the construction of a tomb in Soltaniyeh during his reign, which was built between 703 and 713 AH.

At that time when Oljaytu went to visit Imam Ali tomb and then Oljaytu converted to the Shia religion and decided to transfer the tomb of Imam Ali and Imam Hussein to Soltaniyeh.

The sultan’s goal in building such a unique monument was to bury the body of the first Shia Imam, but he failed to do so as a result of opposition from Shia scholars, and after his death, the site was used as a tomb for himself.

Oljaytu became ill at the age of 34 and after two years he died and was ordered to be buried in the basement of the Soltaniyeh dome. In all available inscriptions, the name of Sultan Muhammad and his son can be seen, and the name of Taj al-Din Alishah can be found somewhere, some of which may have been the architect of the building.

It is not bad to know that 3,000 workers were hired to build it, and the Sultan’s minister, Khaje Rashid al-Din Fazlullah Hamadani, was responsible for designing and overseeing its construction.

Main sections of the Soltaniyeh

Torbat House

On the south side of the building, there is a section known as Torbat-e-Khane, which houses the altar of the complex. Oljaytu ordered to bring the soil of Karbala and Najaf to Soltaniyeh and made this place a holy place.

On the walls of the altar and in front of the door, using Torbat Imam Hussein Sura al-Molk with two lines of Sufi and Kufi roles therefore this part is known as Torbat Khanh.

The gold-plated and octagonal tiles of the building and its porches are amazing, extraordinary, and unique in terms of tile art. In the past, it is said that there were a large copper and gold door between Torbat Khan and the area below the dome that may have been lost or stolen.


The crypt is considered to be one of the lateral spaces on the south side below the Torbat House. Some believe it was built before the dome and used before it was completed.

In keeping with their old ancestors’ beliefs and rituals, the Ilkhanid buried their dead in a crypt in the underground graveyard and placed their ornaments to fit the social status of the individual.

This crypt is the burial place of kings and officials at that time and is accessible through the south porch of the Torbat House. The entrance is low so you have to bend over and respect the dead when you enter.

In the middle of the crypt is the graveyard, with two small spaces on either side. Although excavations at this site did not reveal any tombs in the crypt, historians and some scholars still believe that Sultan Muhammad Khodabandeh was buried in the crypt.


This dome is the first example of a double-shell dome in the world and is of great historical and architectural importance. The height of the dome is about 50 meters and its central span is 25.5 meters.

This dome is 160 cm thick and the gap between the two shells or walls is 60 cm. The double-shelled dome shows the architect’s intelligence that, by creating a hollow space, made the building resistant to earthquakes.

The arch of this dome is very steep and has no examples of crater, height, and structure in Iran. On the exterior of the dome and on all eight sides, arches are part of the ornamentation of the structure.

The minarets in the Soltaniyeh dome are of two types: The minaret is hidden inside the skeleton, and there were eight minarets on top of the building, all except one minaret on the northeast side, and half of the northwest corner minaret collapsed.

The minarets are hollow and have a rotating staircase that extends from the roof to the top of the minaret. In the past, there was a mosaic on each of the minarets, but today there are no traces of them.

These mosaics were evenly distributed throughout the city in order to spread the sound of Azan and news because if there was only one mosque, the great dome would prevent the sound from reaching the whole city.

The minarets do not differ in terms of form, skeleton, and dimensions and give a special impression. Eight symmetrical minarets exited the dome’s propulsion and retained their strength.

Some also believe that these minarets play a devastating role in the building collapsing during the earthquake and preventing damage to the main building. In fact, side porches and eight minarets have been built on the roof to prevent large dome drifts.

Soltaniyeh architecture, a masterpiece of Islamic architecture

The Soltaniyeh Dome Plan has a rectangular shape on the ground floor and first floor and becomes an octagon on the second and third floors.

The style of the facade reflects the Seljuk architecture in mind and there are signs of applying Islamic principles to the structure.

Symbols of Islamic principles include 110 stairs in the building, which is synonymous with the alphabet letters Ali. With regard to Islamic principles, it should also be borne in mind that symmetry is one of the most important principles in architecture and is along the line of symmetry towards Qibla.

The Entrances

In the past, the entrances were 4 ports of varying sizes; large entrances (eastern and northwest entrances) were used by men and small entrances were feminine and reached the small first-floor porches.

Different classes of structures

The ground floor hosts King Mughal’s intended location for the burial of Shia Imams. There is also plenty of space for possibly performing Tawaf and performing religious ceremonies.

The first floor is 9.40 meters high and includes corridors. A corridor (porch) is built around the enclosure and the windows on the four large porches help to illuminate the space.

These corridors were designed to lighten the building because if they were to be filled, they would need a lot of materials and gain more weight. On the first floor corridors, we find chambers probably used by ladies and royal families to watch special ceremonies.

The second floor is 27.80 meters high and features porches like the first floor with a view of the surrounding plains. Tiling, Mogharnas, plastering, and combinations of bricks, tiles, etc., along with numerous inscriptions, have made the porch look special.

These porches were a gathering place for scholars and religious scholars, who in the Safavid era were converted into rooms and used for settlers.

The walls of these rooms were demolished during the overhaul of the Soltaniyeh Dome to prevent the building’s skeleton from becoming heavy and returning to its original form.

Eight staircases are embedded within the walls of the second floor that lead to the minarets and are the second and third-floor communication routes. The stairs are circular and rotary and each stair is 90 cm long and 30 cm high.

On the third floor, where the center of the dome (bottom of the dome) and the octagonal foundations of the minarets are located. This floor is actually on the roof where its proper space allows free movement around the dome and was used to repair the dome or shed snow.

The Soltaniyeh Dome is about half a meter thick, and as we go further, we increase the weight and pressure on the walls, recesses, and empty spaces.

Compact sand floors of 8 to 10 meters’ depth form the ground of this building.  The building is so strong that the 1,600-ton building lasted only 8cm in 700 years and withstood 33 earthquakes, the most severe of which was 6m.

Excellent earth resistance has made the foundations of this massive building very small and shallow, with depths of 50 to 60 cm, and only 1.5 m below the natural surface of the earth has fallen below 1.5 m.

The foundations are made of regular 20 x 25 cm stone blocks and mortar with plaster and lime.

Soltaniyeh Dome Decoration is the peak of art and creativity

Decorations are the first thing that draws attention to Soltaniyeh’s dome and shows the art and concept of the various elements used by the manufacturer. It’s not bad to know that artists have spent three years decorating the building to create a unique masterpiece.

In this building, we have tried to instill in the viewer three important concepts using decorative lines. The words of Allah as the ultimate cause of the universe, Muhammad as the founder of humanity, and Ali as the embodiment of the rule of divine justice.

They have created a combination of the words Allah, Muhammad, and Ali with the combination of Alwan tiles (seven colors) and cold colors, and the same thing has been repeated in the body of the minarets.

The interior porch walls are adorned with the words of Allah, Muhammad, and Ali, created by a combination of blue tile and brick.

Blue is the most important color in decorations as if it were the only color of interest for artists. Due to the lack of technical ways to create colors, a variety of colors ranging from garlic to heavenly blue and even bold green to the dome is seen, but overall a beautiful turquoise color can be seen inside and outside the dome.

There are also wooden lattices made of teak wood and no pins are used in their construction. The wood was brought here by the sultan’s order from India and Lebanon and was immersed in brine before being used in the building to prevent termite damage.

It is also said to have been used in the manufacture of Noah’s ark.

The Secret of Using the Number 8

The Soltaniyeh Dome is generally octagonal with eight doors, eight porches, and eight sympathetic minarets. The reason for using the number 8 is not yet known precisely because it is not sacred like 7 and 12.

However, some have suggested the possibility of creating a sundial, and others point to the strength of the building. On the other hand, some say the building was inspired by the octagonal paradise.

Soltaniyeh ِِDome Sundial

Identifying the time was of great importance to Muslims and played a fundamental role in their religious rituals. For this reason, a sunny clock was placed on the skeleton of the building to minimize the error of time for city dwellers.

The way it works is that if the light shines through the hole in the main dome, it indicates the time of noon. The light shining through the large windows makes the clockwork large and illuminates the small windows for about a minute. At night, the stars seen through these windows also helped to detect time.

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