Citation of all historical texts to the construction of "the largest ever-made brick vault in the Islamic world" by Tajeddin Alishah Jilani, the minister of Sultan Mohammad Khodabandeh Oljaito in the 8th century AH, have always led historians and scholars of architecture to attribute the brick massive U-shaped monument in the center of the historical context of Tabriz to Alishah, Ilkhanid minister. This U-shaped giant vault is mostly considered as the mouth of the same arch, which collapsed shortly due to the haste in the process of its construction in the Ilkhanid period. While new research findings pave the way for new horizons around the identity of the architecture and the use of the contemporary remains of this huge building attributed to the Arch of Alishah. Accordingly, the main question of this leading research will be to determine the architectural relationship of this building with the building constructed in the Ilkhanid Period. If it is assumed that there are two completely distinct phases of architecture, using the dating technique through thermoluminescence method, on the bricks of this huge structure on the basis that brick is one of the desirable building materials for the absolute dating of historical buildings by thermoluminescence method in recent years, there is a time difference of at least two centuries in this existing structure. This indicates the fact that there is no connection between the remains of the arch attributed to the Arch of Alishah and the vault created in the Ilkhanid Period. According to the architectural evidence and conducted studies, what is certain is that modern remains attributed to Alishah Jilani were created about two centuries after the Ilkhanid Period, and the existing U-shaped brick monument is a later construction phase used to block, complete and convert the land use of the remains of the Ilkhanid building of the northern part that have been created on its southern side; so, there is no connection between the existing U-shaped architectural monument and the famous Alishah Arch.