The qa'a (Arabic: قاعة, romanized: qāʿa) is a roofed reception room found in the domestic architecture of affluent residences of the Islamic world. It is the most common hall type in the medieval Islamic domestic architecture. The plan of a qa'a may be inspired by the four-iwan plan (cruciform) of religious buildings. They were used to welcome male guests, where they would sit on the raised platform.
Qa'as are typically found in the homes of wealthy individuals, such as merchants or local political figures. These rooms can be situated on the ground floor or the first floor of a residence and usually face the semi-private courtyard of the house. The qa'a combines elements of a courtyard and an iwan, consisting of a central area called the durqa'a and a raised sitting area known as the tazar. Guests would enter the durqa'a first, and then remove their footwear before being seated on the diwan in the tazar.
The durqa'a is the lower central area of the qa'a, where a cooling fountain, or fasqiya, might be installed to provide sound and refreshment. Flanked by two iwans on either side, the durqa'a serves as the central space for gatherings. The tazar, located in the iwan, is where male guests would be seated and served refreshments. Walls of the tazar often feature recessed shelves displaying decorative items and may include Arabic calligraphy, mashrabiyas, and decorative niches.
The qa'a is heavily decorated, often with vibrant colors and intricate patterns. Wooden panels made of cypress, poplar, or mulberry are common, sometimes layered with gypsum and adorned with metal leaf and paint. Floors are typically inlaid stone, and the ceiling heights vary between the durqa'a and the iwans. The design and decoration of the qa'a reflect the owner's status and serve to impress guests, making it a significant feature of Islamic domestic architecture.