zellij

thumb|A wall covered in zellīj at the Ben Youssef Madrasa in Marrakesh Zellij (), also spelled zillij or zellige, is a style of mosaic tilework made from individually hand-chiseled tile pieces. The pieces were typically of different colours and fitted together to form various patterns on the basis of tessellations, most notably elaborate Islamic geometric motifs such as radiating star patterns composed of various polygons. This form of Islamic art is one of the main characteristics of architecture in the western Islamic world. It is found in the architecture of Morocco, the architecture of Algeria, early Islamic sites in Tunisia, and in the historic monuments of al-Andalus (in the Iberian Peninsula). From the 14th century onwards, zellij became a standard decorative element along lower walls, in fountains and pools, on minarets, and for the paving of floors.

After the 15th century, the traditional mosaic zellij fell out of fashion in most countries except for Morocco, where it continues to be produced today. Zellij is found in modern buildings making use of traditional designs such as the Hassan II Mosque in Casablanca which adds a new color palette with traditional designs. The influence of zellij patterns was also evident in Spanish tiles produced during the Renaissance period and is seen in some modern imitations painted on square tiles.