The Mosallah is another remarkable monument to see in Na'in. Its vast garden used to be a popular recreational area until a few years ago. The mausoleum inside the Mosallah was a pilgrimage site for visitors. The dome of the Mosallah is opposite the dome of the shrine of Emamzadeh Sultan Seyyed Ali and these two are connected by a street. There is a water reservoir on one side of the garden, which can be accessed by people inside and outside the garden through a stairway on each side. Water in this reservoir was cooled by two wind towers. The water reservoir (Persian: ab-anbar) was in use until a few years ago. The architectural style of Na'in's Mosallah is characteristic of the Qajar dynasty and a number of literary, political and religious figures are buried at this site. “Mosallah” is an Arabic word for a place of prayer but, no one knows if any praying was ever done at this location. The Mosallah is an octagonal mausoleum of dervishes and Qajar and Pahlavi political figures. It is encompassed by a Qajar-era military fort with a high wall thick enough for a horse to be ridden along the top. The pistachio trees around the turquoise-domed mausoleum and two tall wind towers make the complex very photogenic. The entrance fee is 50,000 rial and the site is open to the public 08:00-12:00 and again 15:00-17:00.
Mosalla is one of the earliest forms of Islamic architecture. As a rule, it is a large enclosure designated for a communal prayer. It is usually surrounded by a wall and devoid of any architectural or ornamental feature.
The old mosalla of Nain is located to the south from the town's center. Most of its structures have been demolished, and only a domed crypt in the middle of the complex has survived. The new mosalla nearby consists of a beautiful garden enclosed by a high wall. A mausoleum of several local Sufis is located here.