Dayr-e Gachin Caravanserai is located eighty kilometers northeast of Qom. It is known as the mother of the caravanserais of Iran. This monument of ancient Iran is built along the Silk Road and the historical road of Ray to Qom. Today it is in the middle of Kavir National Park. This caravanserai has been registered as a national heritage of Iran.
The structure of Dayr-e Golchin goes back to the Sassanid era and has been repaired during the Seljuk, Safavid and Qajar eras. Historical texts prove that it has also been referred to as Ardeshir, Day-r ol-Jas, Day-re Kaj, too. Among these names, Ardeshir makes it more possible that this building belongs to the Sassanid king, Ardeshir I. It should not be left out that there are other historical buildings such as Rock Castle of Mohammadabad Kaj, Qal-e Goli located close to Dayr-e Gachin.
Dayr-e Gachin Caravanserai is a Chahartaq spread over an area of twelve thousand hectares. It includes different sections. They are gateways, four rectangular towers, two half-towers on two sides of the gate, a three-hundred-square-meter mosque, two Minasaras, a stone mill, a bathhouse, two vestibules, prayer hall, more than forty rooms, staircases that lead to the roof and two wells.
Outside of the caravanserai, a rectangular fire temple was built on its western side, as well as a fortress, brick kiln, two water reservoirs, and a graveyard. Once added to the caravanserai itself, the spread of this historical site reaches nineteen thousand hectares. A wall is surrounding the caravanserai. It is more than five meters tall, one meter wide and eighty meters long. There are crenels in some parts of the wall, which is made of bricks with the cross arrangement. The Sassanid bricks have marvelous details. And they have also been used for the restoration during the Seljuk dynasty.
There is a vestibule after the first gateway. It leads to the Miansara. There are a mosque, bathhouse, mill, and other sections built there. All around this structure, there are thirty-six rooms in one story. All of them have only one door. However, the rooms located higher than the Miansara level have Iwans.
There is an alcove located on the northeast side. The back Miansara that has been built in the form of an octagonal is located there. There are also rooms that each has three doors to the outside.