TEHRAN (Mehr News Agency) -- The third phase of the archaeological excavation started in the Iranian world cultural heritage Takht-e Soleiman, Yousef Moradi director of the archaeologist group who is to work on the ancient monument said on Tuesday.

UNESCO added the site to its World Heritage List on June 29, 2003. The organization has already added the Iran's historical sites Choghazanbil Ziggurat, Persepolis, Isfahan’s Naqsh-e Jahan Square to the list.

"The group intends to conduct studies on Takht-e Soleiman to see if the muddy monuments around the site are related to the Islamic era," said Moradi.

"In the first phase of the project in 2001, a German archaeologist group discovered the plan of the monument's gate and 9 stages of its construction," he added.

According to the studies carried out by the German group, four stages of construction have been done in the Sassanid era and the other five stages are related to Ilkhanids, a Mongol people who controlled eastern Iran from 1256 to 1349. Referring to the second phase of the excavation, he said, "The group succeeded to discover related architectural units to the gate and to find a number of Sassanid muddy seals in the second phase. The group could gain significant information on the Sassanid administrative system."

"Studies indicated that Takht-e Soleiman has been diverted to a township comprised of bazaar, mosque, bathhouse, and settling units after the Ilkhanids devastated the royal monuments of the site," added Moradi.

Located in 45km north eastern off Takab, West Azerbaijan Province, Takht-e Soleiman used to be a fire temple called Azargoshnasb in the Sassanid era.

Azargoshasb was one of the three main fire temples built around the lake located in the region, at the order of Khosro I (531-578 B.C.). Associated with the Jesus’s childhood in Christian legends, the lake is called “Chichast” in Avesta, the sacred Zoroastrian book.

Takht-e Soleiman ruins complex are also attributed to Prophet Solomon.