The site of Soltaniyeh with its impressive dome and monuments reveals an outstanding example of human use of a favourable environment. Moreover, it is an exemplar testimony of an important achievement in the course of human architectural innovations. It was in the fourteenth century when the pasture was selected to become the capital par excellence of an empire. It was the Mongol Ilkhan Oljaytu, recently converted to Shi’ism (and chose the name of Soltan Mohammad Khodābandeh), who decided to build his capital city marked with a huge monument that would become his sepulchre.
The sites reveals the exemplar type of a successful unity between the Mongol way of life,
that is the horse breeding and nomadic way, and the sedentary society prevailing in Iran.
The rapid but astonishingly successful construction of the mausoleum and the structures
of the city in a span of less than ten years (from A.D. 1305 to 1313) was a culminating
point in the history of Persian architecture. The central monument of Soltaniyeh was built
as the mausoleum of the Ilkhān Oljaytu adjacent to the pasture. The mausoleum towered
with a huge brick dome, which soon gave its name to the whole edifice. The monument is
known today as the Gonbad-e Soltaniyeh (the Imperial Dome).
The presence of the highest dome ever constructed on an octagonal plan at Soltaniyeh, which became possible merely by the ingenious constructing of a doubleshelled structure, shows an innovation that inspired the construction of the high dome of Santa Maria del Fiore in Florence almost a century later. The other significant aspect of Oljaytu’s mausoleum is its remarkable interior decorations in the form of glazed tiles, brickwork, marquetry, stuccos and frescoes. The decorated surface in the monument was estimated to 9000 square metres, and is one of the most decorated monuments in Iran. In this way, the monument is a rich “museum” of applied decorative arts and their use in architecture. According to a tradition, the monument had originally been designed to receive the relics of Shi’i imams, Ali and his son, Hoseyn.
The eight minarets entirely in brick around the dome have no structural function, and they are purely decorative.30 The one at the north-eastern corner has been better preserved. The others have been object of restoration during the past years. Each minaret has an octagonal base with a diameter of 2.40. Then it gets a round form at the upper part. Each one had originally a height of 15.5 metres; to this height an extra 3 metres should be added for crowing capitals.
On the side opposite the entrance, that is torbat-khaneh, are the burial chapel and cenotaph of Oljaytu. It is a rectangular addition which was originally covered with a dome. The plan of the torbat-khaneh is, in fact, a trapezoid, and hence its construction had been part of the original plan.31 The main hall is 17.60 m long and 7.80 m wide; its height is 16 m. The building has been vaulted. In the southern wall of the building, there is mihrāb that was once richly decorated with stuccos, tiles and also inscriptions. There are still remains of a Koranic inscription in Kufic on one of the walls. The building was designed to be the tomb of the Ilkhān. So, it is, in fact, the real burial place of the monument.
Under the torbat-khāneh lies a crypt called sardābeh that can be reached by means of a stairway in the southern part of the torbat-khāneh. The sardābeh comprises small niches and rooms of different sizes. According to Hafez Abro, Oljaytu was buried in the sardābeh.