The mausoleum of Oljaytu was constructed in 1302–12 in the city of Soltaniyeh, the capital of the Ilkhanid dynasty, which was founded by the Mongols. Situated in the province of Zanjan, Soltaniyeh is one of the outstanding examples of the achievements of Persian architecture and a key monument in the development of its Islamic architecture. The octagonal building is crowned with a 50 m tall dome covered in turquoise-blue faience and surrounded by eight slender minarets. It is the earliest existing example of the double-shelled dome in Iran. The mausoleum’s interior decoration is also outstanding and scholars such as A.U. Pope have described the building as ‘anticipating the Taj Mahal’ The three storey octagonal structure is the second largest mausoleum in the Islamic world after the Hagia Sophia in Istanbul. The peak of the single egg-shaped dome is 51m above the floor of a main hall which is 25m across with walls 7m thick at the base. Carved stucco work, murals and turquoise painted tiles adorn the inside walls of the building.
Soltaniyeh, located some 240 kilometres (150 mi) to the north-west of Tehran, was built as the capital of Mongol Ilkhanid rulers of Iran in the 14th century. Its name which refers to the Islamic ruler title sultan translates loosely as “the Regal”. Soltaniyeh was visited by Ruy González de Clavijo, who reported that the city was a hub of silk exportation.
Soltaniyeh is state owned, and protected as a national monument on the basis of the Iranian Law on the Conservation of National Monuments (1982) and the Law on City Properties (1982). Parts of the buffer zone are in private ownership. The principal management authority of the property is the Iranian Cultural Heritage, Handicraft and Tourism Organization (which is administered and funded by the Government of Iran) through its local office in Zanjan. There is a management plan with short-term (1-year), mid-term (3-year), and long-term (5-year) objectives related to equipment, research, restoration and conservation, and development of tourism at Soltaniyeh. Financial resources for the property are provided through national budgets.
In 2005, UNESCO listed Soltaniyeh as one of the World Heritage Sites. The road from Zanjan to Soltaniyeh extends until it reaches to the Katale khor cave.
