Sultanieh dome is a great structure built when Mongolians ruled Iran in Sultanieh city.This building was so famous in its time that became the inspiration for Saint Maria Del Fiore in Florence of Italy. The main color of Sultanieh is blue in different hues from pale to sky ,turquoise and deep blues.8 spiral stairways connect the stories. Sultanieh dome is a unique turning point in Islamic architecture from the view point of architecture style, connection between spaces, proportion of different components, stability, aesthetic aspects and ornamental features. It has been mentioned in many travel logs and historical resources and many orientalists emphasized its glory and importance.
Sultanieh dome is the most important structure of the city which was built by order of Sultan Mohammad Khodabande to be an octagonal tomb with eight minarets and a turquoise mosaic dome. Quran verses in Suls and Kufi are written all over the walls and cornices making it the greatest architecture of Ilkhanid period.
This large dome with 50.5 meters height and 30.6 meters diagonal is the oldest two-layered dome in the world. The dome is also a solarium, the light passing through small windows show minutes and the larger ones show hours.
Sultanieh dome was registered as a world heritage site in 2006.
Saint Maria Del Fiore and its dome with red bricks is the symbol of Florence which many think is inspired by Sultanieh dome in Zanjan. It took 170 years to build this cathedral. The dome is two-layered with 32 meters height and 42 meters diagonal. The nine circles of the inner dome is painted with apocalypse images. Arnolfo, architecture of the medieval period, started building the Gothic Cathedral but his work was finished by Brunelleschi after his death.