The complex of underground structures in the town of Nushabad, Shahrestana Kashan, which is an underground city called "Ui", causes constant amazement among all visitors of this historical monument. The village of Nushabad, the former capital of the state during the reign of padishah Anushirvan from the Sassanid dynasty, is located 10 km north of the city of Kashan, west of the cities of Aran and Bidgol shahrestan Kashan. This underground complex, which has a one and a half thousand years of history and was built in Sassanian Iran, was used by the population as a refuge and salvation from enemies in the turbulent years of military raids. The underground passages were accidentally discovered by one of the residents, who was going to dig a well in the yard of his house. Since the real entrance to the underground city was never found, an underground reservoir is used to enter it,located next to the city.
The underground city "Ui" is an extensive and complex system of narrow intersecting corridors and small rooms located under the space of the old city and capturing its modern parts. With the exception of the very entrance to the structure, the height of all the interior rooms of the underground city "Ui" is comparable to the average human height and ranges from 170 to 180 cm.
Ventilation system of the underground city
The ventilation of the underground city in Nushabad was carried out by means of canals, which were laid from the upper to the lower level of this structure. Connecting shafts, in addition to ensuring movement between levels, served to penetrate air to the lower floors. The same principle was applied in wells leading to internal water channels. The underground spaces were accessed through a well and a narrow short channel. The defensive nature of this underground structure and its use as a refuge left an imprint on the details of the architectural arrangement, planned in such a way that entering these underground spaces was the greatest challenge.
The inner space of the city was illuminated with ceramic oil lamps. The oil for them was most likely produced at two ancient oil mills located in Nushabad. In turbulent times, when people were forced to hide underground, they used water from underground wells and canals.
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Asylum structure
When residents descended into the underground city to find shelter from enemies, a soldier walked in front of everyone, illuminating the route with a lamp. The same soldier, who closed the line of people, extinguished the lamps so that the enemies would not find their way into the inner spaces. The corridors were so narrow that it was only possible to move along them one at a time. In some mines, you have to go bent over, and there are places where you can only crawl.
The inner rooms are built in the form of a suite and are interconnected by winding corridors so that one cannot immediately see the next room. In the walls of some rooms, at a height of 3-5 meters, rounded holes are visible, which can be penetrated with great difficulty and which connect the floor with the following levels. These passages are also built in the shape of the Latin letter L.
The total length of the historical monument, which begins at a depth of 4 meters below the city level and stretches to a depth of 16 meters, is unknown. But taking into account the available evidence and stories of local residents, it stretches to the ancient fortress walls of the city, and its area is 4 square kilometers.
The spaces that have been explored to date are spread over three floors and include narrow corridors and quadrangular vaulted rooms carved into the walls. The communication between the floors is carried out using vertical shafts with a depth of 5 to 7 meters.
Passages
The passages to the next floors were arranged in such a way that everyone who had the intention of getting into these rooms was forced to move from the bottom up, which almost completely deprived the attackers of the ability to defend themselves, and gave a sufficient advantage to confront the enemy.
Unfortunately, water leaks and seepage of the city sewer into the inner space of the underground city led to the formation of high humidity and wetting of the walls, as a result of which the walls acquired the consistency of clay. This circumstance prevents the continuation of excavations and further study of this national monument. Meanwhile, it would be appropriate to pay tribute to this unique object, which is the largest structure of its kind in the world, and to make efforts to complete the excavations and introduce it to all the inhabitants of the planet.
