tomb of the Dome of Soltaniyeh and an adjacent khanaqah, a building designed specifically for Sufi gatherings as a spiritual retreat. The quality of the preserved tomb attests to the richness of its patronage by the Sultan Oljeitu. The large domed tomb chamber of Oljeitu was meant to rival the colossal tomb built by the Seljuq Sultan Sanjar at Merv in 1157. The tomb of Oljeitu has an octagonal plan, like the Tomb of Ahmed Sanjar, with both complexes being sponsored by the Ilkhanid court and were considered some of the most prestigious buildings at the time. The Global Heritage site of Gonbad-e-sultaniyeh has been recognised as a UNESCO World Heritage Site since 2005. It followed the specific historic UNESCO criteria landscape of four characteristics: ancient and historical monuments, farms, urban landscapes, and the Historical Grass of Soltaniyeh. Architecture and interior design The Dome of Solteniyeh was one of the largest religious endowments of the 14th century, and was utilized for multiple functions, such as Quran reading, praying, teaching, housing, and medical purposes. The main building is approximately 125 feet across and is crowned by a dome with an average diameter of 80 feet. The tomb is highly visible, due to its unique incorporation of eight minarets enclosing the dome above the gallery. More specifically, Oljeitu’s complex consists of four iwans connected by arcades with muqarnas surrounding the perimeter of a courtyard. The tomb itself stands behind the southern iwan. Furthermore, the iwans were all plastered and painted, and the courtyard was paved with white marble. The construction of the double-shelled dome employed an interlocking arched herringbone network. The Dome of Soltaniyeh was one of the first to use this pattern in Iran, and is unique in choosing brick for its material as previous similar architectural structures often utilized wood. As for the interior of the tomb, it is decorated in tile and plaster. The insides of the iwans’ walls possess white inscriptions that stand out against the blue background. The underside of the iwans are stuccoed with bands of ornament, that were later painted. A significant inscription--outlined with ogival forms sculpted over cloth--circles the entire dome. The galleries have low, wooden or marble railings. The windows are fitted with bronze screens, along with bronze knobs and balls set with gold and silver. Some elements from these window grilles were inscribed with their patron’s name or with detailed scenes, such