The Haydariyya mosque in the Bolaghi district of Qazvin is a monument from the Seljuk period, presumably from the late 12th or early 13th century. Under the Qajar dynasty in the 19th century, this mosque was incorporated into the structure of a madrasa. However, most parts of this madrasa were later demolished to make way for the construction of an elementary school in 1955. The stylistic features of the Haydariyya mosque resemble those of the Friday Mosque of Qazvin, and it is therefore assumed that the Haydariyya Mosque was built or renovated by the same architect.

The mosque consists of a single domed chamber prayer hall. This mosque was located on the south side of a courtyard, which was surrounded by the madrasa's arched cells on its east, west and north sides. Based on André Godard's plan of the madrasa, the entrances to the complex were located on the northeast and northwest of the courtyard, and there were once nine cells on the east and west sides next to the entrances. The north side of the madrasa was comprised of a central iwan flanked by three cells on each side.

According to Arthur Pope's plan of the Haydariyya Mosque, the square plan of its Seljuk prayer hall is 14 by 14 meters on the outside and 10 by 10 meters on the mosque's interior. The mosque is entered from the north, where an entrance iwan, measuring 6 by 14 meters, was later added to the Seljuk structure. The domed chamber of this mosque is structured similarly to Sasanid chahar taq fire temples, within which the square plan is transformed into an octagon via squinches that support a brick dome. However, the dome of this mosque is no longer extant. A recent temporary roof now protects the interior space.

The mosque is constructed of brick and is famous for its splendid brickwork facing and carved stucco decorations. Additionally, its decoration is remarkable for its early glazed tiles. Arched niches in interior corners are topped with carved stucco inscriptions and muqarnas brick decorations. The rhombus brick patterns on the squinches are decorated with inscribed bas-relief circles. There is also a fine floriated Kufic plaster inscription frieze below the dome arches. Some of the inscriptions are from of the Surah Hashr in the Quran.

The mihrab on the south wall of the prayer hall is composed of finely carved stucco on a painted blue background. Although the bottom half of the mihrab has been damaged, it remains one of the finest examples of Iranian stucco mihrabs. Stylized high relief pomegranates and pine cones are found on the frame around the mihrab and on the arch of the dome above the mihrab.

Sources:

Filmer, Henry. The Pageant of Persia: A Record of Travel by Motor in Persia with an Account of Its Ancient and Modern Ways, 283-284. Indianapolis, New York: The Bobbs-Merrill Company, 1936.

Godard, André. The Art of Iran, 224, 227,281. New York: Praeger, 1965.

"Heidarieh Mosque." Iran Tourism & Touring Organization of Qazvin. http://www.qazvintourism.com/historical/ecaption.asp?id=3&id1=school. [Accessed August 20, 2010; inaccessible October 31, 2013]

"Masjid-i Heidarieh." Iranshahr: Encyclopaedia of Iranian Architectural History. http://iranshahrpedia.ir/fa/%D8%AD%DB%8C%D8%AF%D8%B1%DB%8C%D9%87%D8%8C_%D9%85%D8%B3%D8%AC%D8%AF. [Accessed August 13, 2010; inaccessible October 31, 2013]

"Qazvin." In The Grove Encyclopedia of Islamic Art and Architecture, edited by Bloom, Jonathan M., and Sheila S. Blair. : Oxford University Press, 2009. http://www.oxfordreference.com/view/10.1093/acref/9780195309911.001.0001/acref-9780195309911-e-762. http://www.oxfordreference.com/view/10.1093/acref/9780195309911.001.0001/acref-9780195309911-e-762. [Accessed August 13, 2010; updated October 31, 2013]

Schroeder, Eric. "The Seljuq Period." In A Survey of Persian Art from Prehistoric Times to the Present, edited by Pope, Arthur Upham and Phyllis Ackerman (assistant editor), Vol. 3 Architecture, Its Ornament, City Plans, Gardens, 3rd ed., 1020-1021. Tehran: Soroush Press, 1977.