Iwans were a trademark of the Sassanid architecture of Persia, later finding their way into Islamic architecture. This transition reached its peak during the Seljuki era when iwans became established as a fundamental design unit in Islamic architecture. Typically, iwans open on to a central courtyard, and have been used in both public and residential architecture.
Iwan mosques are most notable for their domed chambers and iwans, which are vaulted spaces open out on one end. In iwan mosques, one or more iwans face a central courtyard that serves as the prayer hall. The style represents a borrowing from pre-Islamic Iranian architecture and has been used almost exclusively for mosques in Iran. Many iwan mosques are converted Zoroastrian fire temples where the courtyard was used to house the sacred fire. Today, iwan mosques are seldom built. A notable example of a more recent four iwan design is the King Saud Mosque in Jeddah, Saudi Arabia, finished in 1987.
