The Soltaniyeh Dome in Zanjan: The Largest Brick Dome in the World
Wandering through the captivating city of Zanjan is always an exciting and unexpected adventure. At any moment, you might stumble upon a centuries-old structure or a bustling historical bazaar. From traditional bathhouses to ancient mosques, Zanjan has countless stories to tell about Iran’s rich history. Just a visit to a few of its attractions is enough to reveal the depth of heritage and authenticity embedded in this magnificent city.
Among all the historical landmarks of Zanjan, one stands out in both splendor and fame—a structure whose turquoise dome has become legendary. This monument alone embodies the city’s historical identity and has earned admiration from even the harshest critics with its stunning and intricate design: the glorious Soltaniyeh Dome, an architectural masterpiece that showcases the pinnacle of Iranian-Islamic architecture and is considered one of the most iconic heritage sites in the world.
Why Visit the Soltaniyeh Dome?
It is the largest brick dome in the world and the third tallest dome globally, after Santa Maria del Fiore and Hagia Sophia.
Its unique architectural style has inspired the construction of several renowned buildings around the world.
It is one of the most beautiful and must-see attractions in Zanjan.
It remains one of Iran’s most structurally resilient historical monuments.
With immense historical and cultural value, it has been registered as a UNESCO World Heritage Site.
A Brief History of Soltaniyeh Dome
According to many historians and scholars, the Soltaniyeh Dome was built between 704 and 712 AH (1304–1312 AD) by the order of the Ilkhanid ruler Mohammad Khodabandeh (Oljeitu). During his reign, he founded the city of Soltaniyeh and moved the capital of the empire from Tabriz to this newly established city.
After converting to Islam, Oljeitu sought to construct a magnificent Islamic monument in Soltaniyeh. He gathered some of the most prominent architects in the country and commissioned the construction of a beautiful and enduring masterpiece. Time has proven his vision right—700 years later, the dome still stands, firm and awe-inspiring.
Architectural Marvel of Soltaniyeh
What has protected the Soltaniyeh Dome from the destructive forces of time and nature over the centuries is undoubtedly its ingenious and unique architecture. Despite weighing around 1,600 tons, the structure has only settled by 8 centimeters in 700 years—an astonishing feat of Iranian-Islamic engineering.
The architectural style of the dome bears a strong resemblance to the Seljuk era, particularly in its octagonal second and third floors, which are ingeniously set within a rectangular ground floor plan. The core structure is made of brick, while the dome itself is adorned with beautifully patterned turquoise tiles.
Inside, the monument is divided into various sections such as the crypt (sardabeh), tomb chamber (torbat-khaneh), and the main dome hall (gonbad-khaneh)—each featuring stunning inscriptions, decorative motifs, and verses from the Quran. The exceptional design and elegance of this monument have even earned praise from international scholars.
Arthur Pope, one of the most distinguished American Iranologists, described the Soltaniyeh Dome as:
“A solid structure in which every single element has been placed exactly where it should be to create such a beautiful masterpiece.”
Pope even believed that the architectural design of India’s Taj Mahal was inspired by the Soltaniyeh Dome.
Different Sections of the Soltaniyeh Dome
From a distance, the Soltaniyeh Dome appears as a single, standalone dome. However, the structure is made up of several key architectural components.
The Torbat Khaneh (Sanctuary Chamber)
Located on the southern side of the dome, this section contains the mihrab (prayer niche). Measuring 18 meters in length, 16 meters in height, and 8 meters in width, the Torbat Khaneh was added after the completion of the main dome. Interestingly, soil from the holy cities of Karbala and Najaf was used in its construction. After failing to relocate the remains of Imam Hussein (AS) and Imam Ali (AS) to this mausoleum, Sultan Mohammad Khodabandeh ordered the transport of sacred soil from those cities to be used in the dome.
On the walls of the mihrab and opposite the main entrance, Surah Al-Mulk from the Quran is inscribed in Kufic and Thuluth scripts using the soil of Imam Hussein’s burial ground, giving this section its name, the “Torbat Khaneh.”
The golden octagonal tiles used here are intricately decorated and cover the lower walls up to one meter in height. These rare and artistic tile works are highly valued. Some historians believe a massive door made of gold and copper once existed here but was either stolen or destroyed.
The Crypt (Sardabeh)
Beneath the dome lies the crypt, located precisely under the Torbat Khaneh. Believed to be constructed before the dome itself, it was used during earlier stages of the project. In line with Ilkhanid burial customs, nobles and royals were interred here with jewelry and belongings, symbolizing their status.
The crypt is accessible through the southern porch of the Torbat Khaneh. Its low entrance forces visitors to bow, symbolizing respect for the deceased. Although no graves were found in recent excavations, some historians believe that Sultan Mohammad Khodabandeh may have been buried here.
The Dome Chamber (Gonbad Khaneh)
The Soltaniyeh Dome is one of the earliest known double-shell domes in the world, a significant architectural and historical innovation. The dome stands about 50 meters tall, with an internal diameter of 26 meters and an external diameter of 38 meters. It has a wall thickness of 160 cm and a 60 cm hollow space between the two shells, making it highly resistant to earthquakes.
The dome’s sharp curve and structure are unique in Iran. From the exterior, each of the eight sides displays decorative arches, showcasing intricate architectural details.
The Minarets
There are two types of minarets: visible minarets atop the dome and hidden ones within the structure. Originally, eight minarets crowned the dome, but only two partially remain today. These were symmetrical in design and added grandeur to the building.
The hollow minarets contain spiral staircases that connect the third-floor porches to the roof. Muezzins once used these to broadcast the call to prayer uniformly across the city. The symmetrical placement of these minarets also helped counteract the outward force of the dome and provided structural reinforcement. Some researchers believe the minarets were designed to collapse in earthquakes, protecting the main dome.
Ruined Sections
Parts of the royal citadel, surrounding buildings, and a defensive structure including 16 bastions and a moat have been destroyed. Some inscriptions were ordered removed by Miran Shah, son of Tamerlane. Once public benefit spaces, the surrounding areas have now vanished.
Remnants of a plastered mosque mihrab on the southern side indicate that another significant structure once stood beside the mausoleum.
Architectural Design of the Soltaniyeh Dome
The ground and first floors follow a rectangular plan, while the second and third floors are octagonal. The style mirrors Seljuk architecture, incorporating Islamic principles—for example, the 110 steps in reference to Imam Ali’s name in abjad numerals, and perfect qibla alignment.
Brick is the primary material, with the dome covered in glazed turquoise and lapis lazuli tiles using mosaic techniques. The mortar is a mixture of gypsum and lime.
Researchers believe the dome’s design was inspired by the mausoleum of Ghazan Khan, which itself was influenced by Sultan Sanjar’s tomb. However, while Ghazan Khan’s tomb was square, Soltaniyeh’s is octagonal.
Architectural Marvels
The Soltaniyeh Dome inspired Gothic architecture. Italian architects Brunelleschi and Lorenzo Ghiberti are believed to have based Florence’s Santa Maria del Fiore dome on Soltaniyeh’s design. Arthur Pope, a prominent American historian, argued that the Taj Mahal was also influenced by it.
Despite having a shallow foundation—just half a meter—the dome, weighing 1,600 tons, has only settled 8 cm in 700 years and has withstood 33 earthquakes, the strongest measuring 6 on the Richter scale. The compacted sandy ground beneath provided high support with a foundation depth of just 50–60 cm, built from 20×25 cm stone blocks with lime and gypsum mortar.
Hidden Symbols and Secrets
The Mystery of the Number Eight
The dome has eight sides, eight porches, eight doors, and eight minarets. Although not a sacred number like 7 or 12, some believe eight was used to create a sundial or for structural strength. Others suggest it symbolizes the eight gates of paradise.
The Dome’s Sundial
To help Muslims determine prayer times accurately, a sundial was integrated into the building’s skeleton. When sunlight hits the dome, it marks noon. Large windows act as hour hands, and smaller windows show minutes. At night, stars visible through the windows also indicate time.
Decorative Elements
Islamic Motifs
Throughout the structure, inscriptions of the words “Allah,” “Mohammad,” and “Ali” appear in colorful tilework. Blue tones dominate the building, even on the minarets. Other phrases like “Subhanallah” and “La ilaha illallah” repeat rhythmically in geometric patterns. Initially, the decorations were done in tiles and bricks, but later Sultan Mohammad Khodabandeh ordered them to be covered with plaster and re-inscribed.
Use of Blue
Blue is the most prominent color, ranging from deep navy to sky blue and teal. It was the only color used for decoration, giving the dome its distinct identity.
Wooden Decorations
Decorative elements made from teak wood—imported from Lebanon and India—were used without nails. Craftsmen soaked the wood in saltwater to protect it from termites. Some legends claim Noah’s Ark was also made from teak.
Inscriptions
Various Quranic verses appear throughout the dome: Surah Al-Fath encircles the ground floor, Ayat al-Kursi is above the main entrance, Surahs Al-Ikhlas, Al-Anbiya, Al-Mulk, and Al-Mu’minun are inscribed on the walls. Additional inscriptions include repeated mentions of Ali, Mohammad, “Subhanallah” (six times), and phrases like “Mohammad Rasulullah” and “Sultan Zillullah.”
How Much Time and Money Should You Plan for Visiting the Soltaniyeh Dome?
A visit to the magnificent Soltaniyeh Dome and its breathtaking architecture typically takes about one hour. Please note that there is a small entrance fee required to access the site.
What’s the Best Time to Visit the Soltaniyeh Dome?
To enjoy your visit in pleasant weather, the best time to travel to Soltaniyeh is from May to July (Ordibehesht to Tir in the Iranian calendar). This season also gives you the opportunity to explore other beautiful natural and historical attractions in the Zanjan region.
How to Get to the Soltaniyeh Dome
The Soltaniyeh Dome is located in the heart of Soltaniyeh city, within the Soltaniyeh Citadel complex.
To reach it, first travel to the historical city of Zanjan. From there, take the road toward Qazvin, and after around 30 kilometers, turn right onto the Soltaniyeh Road. The dome awaits you in the beautiful city of Soltaniyeh.
Nearby Attractions Around the Soltaniyeh Dome
Salar Historical Bathhouse – 300 meters
Noor Hill – 1 kilometer
Tomb of Chalabi Oghlu – 1 kilometer
Tomb of Molla Hassan Kashi – 1.8 kilometers
Soltaniyeh Fortress – 2.6 kilometers
Hotels Near the Soltaniyeh Dome
Shandiz Suites – 160 meters
Shahre Aftab Hotel, Abhar – 33 kilometers
Zanjan Tourism Hotel – 40.3 kilometers
Payam Hotel, Zanjan – 41.3 kilometers
Restaurants Close to the Soltaniyeh Dome
Setareh Shahr Restaurant – 53 meters
Sadaf Restaurant – 170 meters
Saffron Restaurant – 500 meters
Kosar Banquet Hall & Restaurant – 700 meters
Golriz Restaurant – 850 meters
