Muqarnas (Arabic: مقرنص Persian: مقرنس) is a type of corbel employed as a decorative device in traditional Islamic and Persian architecture. The related mocárabe refers only to projecting elements that resemble stalactites, alveole.
An architectural ornamentation reminiscent of stalactites, muqarnas developed around the middle of the 10th century in northeastern Iran and almost simultaneously — but seemingly independently — in central North Africa; they take the form of small pointed niches, stacked in tiers which project beyond lower tiers, commonly constructed of brick, stone, stucco, or wood, clad with painted tiles, wood, or plaster, and are typically applied to domes, pendentives, cornices, squinches and the undersides of arches and vaults.
Examples can be found in the Alhambra in Granada, Spain, the Abbasid Palace in Baghdad, and the mausoleum of Sultan Qaitbay, Cairo, Egypt. Large rectangular roofs with muqarnas-style decoration adorn the 12th century Cappella Palatina in Palermo, Sicily, and other important buildings in Norman Sicily.