A Masterpiece of Islamic Architecture
In the historic city of Soltaniyeh, located in Zanjan Province, Iran, stands a magnificent turquoise-colored dome that dominates the skyline—the Dome of Soltaniyeh. This architectural marvel, a UNESCO World Heritage Site, is recognized as the largest brick dome in the world and a shining example of Persian-Islamic architecture.
Each year, this architectural gem attracts thousands of international and domestic tourists who are fascinated by its grandeur and historical significance. Since 1969, extensive restoration efforts have been carried out, with the dome undergoing nine restoration phases to preserve its beauty and structural integrity.
Soltaniyeh Dome: A Global Architectural Marvel
The Dome of Soltaniyeh holds significant global importance:
- It ranks as the third-largest brick dome in the world, following Santa Maria del Fiore Cathedral in Italy and Hagia Sophia in Turkey.
- It is Iran’s largest historic dome and the world’s largest brick dome.
- This architectural wonder has inspired the design of Santa Maria del Fiore Cathedral in Italy and Taj Mahal in India.
- It is considered the first double-shell dome in history, a pioneering innovation in architecture.
- The dome weighs 1,600 tons, yet it has remarkably remained standing for over 700 years with only an 8-centimeter settlement.
The Architecture of the Soltaniyeh Dome: A Testament to Innovation
The Dome of Soltaniyeh is a three-story structure, inspired by Seljuk architecture. The ground and first floors follow a rectangular layout, while the upper floors transition into an octagonal shape, each side measuring 17 meters.
Though the significance of the octagonal design remains uncertain, some theories suggest it was inspired by the eight doors of paradise in Islamic tradition, while others argue it was a structural choice for enhanced stability and seismic resistance.
The dome’s height reaches 50 meters, with a central opening diameter of 25.5 meters, making it an engineering feat. The double-shell construction, with a 160 cm thick structure and a 60 cm gap between layers, provides exceptional stability against earthquakes.
The main building material used in the dome is brick, with turquoise and cobalt blue tiles adorning its surface in exquisite mosaic patterns. The mortar used in its construction consists of gypsum mixed with lime, ensuring durability.
Notably, the dome follows Islamic numerical symbolism, incorporating 110 steps, a number that corresponds to the name of Imam Ali (a.s.) in Abjad numerology.
Key Sections of the Soltaniyeh Dome
The structure consists of three main sections, each with significant historical and religious importance:
- The “Turbat-Khaneh” (Sanctuary of Holy Soil)
Located on the southern side of the dome, the Turbat-Khaneh (meaning “House of Sacred Soil”) was built upon the order of Sultan Öljaitü. Since he was unable to relocate the remains of Imam Ali (a.s.) and Imam Hussein (a.s.) from Najaf and Karbala, he ordered sacred soil from their graves to be brought and mixed into the structure’s foundation.
The intricate tilework in this section, featuring golden-hued tiles with eight-sided star motifs, is one of the finest examples of Persian tile-making artistry.
- The Crypt (Sardabeh)
Beneath the Turbat-Khaneh, a crypt is situated, which was likely constructed before the dome itself. Ilkhanid rulers followed their Mongol ancestors’ burial traditions, interring the deceased in subterranean crypts, often with valuable artifacts reflecting their social status.
While no tombs have been discovered within the crypt of Soltaniyeh, many historians still believe that Sultan Öljaitü was buried here.
- The Dome Chamber
The main dome chamber is the heart of the structure, towering at 50 meters with a vast open space below. Its double-shell design not only enhances aesthetic appeal but also provides earthquake resistance.
Supporting the dome are eight massive brick piers, each with a surface area of 50 square meters, bearing a load of 200 tons.
Artistic and Decorative Features of the Soltaniyeh Dome
The Dome of Soltaniyeh is renowned for its sophisticated decorative elements, including:
- Intricate Calligraphy and Kufi Inscriptions
The dome showcases Islamic calligraphy featuring sacred words:
- “Allah” (God) represents the Creator of the universe.
- “Muhammad” symbolizes the Prophet of Islam.
- “Ali” signifies the essence of justice and divine governance.
These names appear in mosaic tilework across the dome and its eight minarets, arranged in complex geometric patterns.
- Multi-layered Ornamentation
The structure contains two distinct layers of decoration:
- The first layer consists of elaborate brickwork and tile designs.
- The second layer, added later, features gypsum-based inscriptions covering the original tilework.
This technique highlights the importance of visual storytelling in Islamic architecture.
- Use of Vibrant Colors
The dominant color in the dome’s interior and exterior decoration is turquoise blue, complemented by shades of deep blue and green. These colors symbolize paradise and create a sense of spiritual transcendence.
- Wooden Screens and Starry Patterns
The dome incorporates intricately carved wooden latticework, made from teakwood imported from India and Lebanon. These screens were designed to filter light into the interior, mimicking the stars of the night sky.
Soltaniyeh’s Structural Genius: Engineering Marvels
- Earthquake-Resistant Dome
The Soltaniyeh Dome has withstood 33 earthquakes, including those reaching 6.0 on the Richter scale, demonstrating exceptional engineering foresight.
- Solar Clock for Timekeeping
Embedded within the dome’s architecture is an ingenious solar clock. Sunlight entering through the central oculus indicates the exact time of noon, while smaller windows track hours and minutes.
At night, star constellations visible through these openings further assisted with timekeeping.
- Underground Foundations and Structural Stability
The foundation consists of compressed sand and gravel layers measuring 8–10 meters deep, providing a stable base. Despite its enormous weight (1,600 tons), the dome has only settled 8 centimeters in 700 years.
Read More: Hooshang Seyhoun : The Legacy of an Iconic Iranian Architect
Historical Impact and Global Influence
The Soltaniyeh Dome played a pivotal role in shaping global architecture, influencing:
- Gothic architecture in Europe.
- The design of Santa Maria del Fiore Cathedral in Florence, Italy.
- The Taj Mahal in India, which adopted elements of its dome structure.
Preservation and Restoration Efforts
For 25 years, the Soltaniyeh Dome remained neglected, leading to significant deterioration. In 1969, Italian conservation experts initiated an extensive restoration project, which continued until 1979. Restoration work remains ongoing, ensuring that future generations can experience this timeless masterpiece.
Conclusion
The Dome of Soltaniyeh is not just an architectural landmark; it is a testament to Persian engineering ingenuity. As the largest brick dome in the world, it continues to captivate historians, architects, and visitors alike, serving as a symbol of Iran’s rich cultural heritage and an enduring legacy of Islamic architecture.
