In architectural archaeology, the term iwan refers to a large, vaulted hall with a vaulted front opening onto a hall or courtyard by means of an arch of any type, and a closed rear wall. It is also a spacious structure with a roof supported by an arch at the front, where dignitaries sit. It is thus a square or rectangular architectural unit with a vaulted ceiling, often flat, and surrounded by three walls on only three sides. The fourth side is open by an arch of any type. If this fourth side is closed, the iwan is then called a council. The floor of this iwan usually rises approximately one step above the floor of the hall or courtyard preceding it.

The iwan has been used specifically in Islamic Madrasa architecture since the Seljuk era. A Madrasa comprises a square or rectangular courtyard, which may be opened by a single iwan (the qibla iwan), or by two iwans facing each other, or by four axial iwans, the largest of which is the qibla iwan. One of the most prominent examples of this in Egypt is the Sultan Hassan Madrasa in Cairo, where the qibla iwan is the largest after the iwan of Khosrow.

Iwans were also found in other Islamic buildings, such as khanqahs and mosques.

Architectural Characteristics of the Iwan:

It is rectangular or square in shape.

It is surrounded by three walls, while the fourth side is open without doors.

The Iwan is often raised by a step or staircase above the floor level of the courtyard.

Its ceiling is either flat or arched.

Its facade is decorated with a prominent architectural arch.

Iwans are commonly found in religious and educational facilities such as madrasas, mosques, khanqahs, inns, and hospitals. If the open side is closed off by a fourth wall, the Iwan loses its design nature and becomes merely a room.