According to some historical accounts, Öljaitü (who chose the name "Muhammad Khodabandeh" after converting to Shi'ism) intended to transfer the blessed bodies of Imam Ali (PBUH) and Imam Hussain (PBUH) to Soltaniyeh. Although this plan was not realized due to opposition from the scholars of Najaf and Karbala, his determination to build a grand and magnificent structure resulted in a dome that stands today not only as his own mausoleum but as a symbol of the grandeur of Iranian-Islamic architecture.
Built between 704 and 712 AH (1302-1310 AD), this structure is one of the largest and tallest historical brick domes in the world. The height of this massive dome is approximately 48.5 meters, and its internal span diameter is 25.5 meters.
Soltaniyeh was the capital of the Ilkhanid government during Öljaitü's time. The structure, originally designed to serve as a mausoleum for Imam Ali (PBUH) and Imam Hussain (PBUH)—which is why it is also known as the "Dome of Imam Ali" or "Dome of Hussain"—later became Öljaitü's tomb. Today, it is recognized as one of the eight Iranian sites inscribed on the UNESCO World Heritage List (2005). The identity of the architect or architects of the building is not definitively known in historical sources, but the immense engineering evolution achieved in this structure was the result of the vast financial resources of the Ilkhanid government and the efforts of outstanding Iranian master craftsmen of that era.
From an architectural perspective, the Soltaniyeh Dome is one of the first and most important examples of a "double-shell dome" in Iran and the Islamic world. Its advanced technology later garnered attention and admiration from Italian Renaissance architects (particularly in the construction of the dome of the Cathedral of Santa Maria del Fiore in Florence). Some architectural historians view the astonishing structural similarities between the Soltaniyeh Dome and the Florence Cathedral as a sign of the indirect influence of the Iranian engineering tradition on Renaissance architecture; although this hypothesis has not been definitively proven, the extent of the Florentine architects' direct access to the plans of this building remains a subject of scientific debate.
In terms of structure and engineering, the Soltaniyeh Dome is an unparalleled marvel of brickwork and stability. The dome consists of two shells: the inner shell (visible from the inside) with a height of 35 meters and a thickness of 50 centimeters, and the outer shell with a height of 48.5 meters and a thickness of 80 centimeters. The space between the two shells is approximately 2.5 meters, where corridors have been incorporated to reduce weight and increase stability. To transfer the dome's load to the octagonal walls, Ilkhanid architects used an advanced system of "squinches" and "pendentives," which convert the octagon into a circle. Around the dome, there were eight tall minarets (only two of which remain fully intact today) and massive iwans with azure, turquoise, and gold tile work, much of which was unfortunately destroyed over subsequent centuries. The interior of the dome is a treasure trove of stucco work, Quranic inscriptions, and geometric patterns; the 35-meter-high interior walls are covered with brick stucco featuring arabesque designs, Kufic brickwork, and Thuluth script, while the light wells installed beneath the dome grace the interior with miraculous natural light.
The influence of the Soltaniyeh Dome on world architecture transcends the borders of Iran and even the Islamic world. One of the most cited examples of this influence is its inspiration for the masterpiece of Indian Mughal architecture, the Taj Mahal (built in 1653 AD). The Taj Mahal, designed by the Iranian architect "Ustad Ahmad Lahori," follows a double-shell structure and weight-transfer principles similar to those of Soltaniyeh. UNESCO has described the Soltaniyeh Dome as "anticipating the Taj Mahal," although its impact on the Timurid and Mughal architectural periods is defensibly classified as an "indirect inspiration." The dome of the Süleymaniye Mosque in Istanbul (designed by Mimar Sinan, 1557 AD) and the Jama Masjid in Delhi (India) also bear traces of the Iranian double-shell dome technology.
The Soltaniyeh Dome is living proof that the Iranian-Islamic civilization was not introspective, but rather acted as one of the primary exporters of architectural technology and art to the world. This building demonstrates how, in the 14th century, Iranian engineers were able to elevate architecture to a level of complexity that centuries later inspired Renaissance architects in Europe and the Mughals in India.
The Soltaniyeh Dome is a "living museum of scientific-cultural interactions" in the region—interactions that spanned Iran, India (the Mughals), Turkey (the Ottomans), and even Europe. Althou…