Optical illusionIn visual perception, an optical illusion (also called a visual illusion) is an illusion caused by the visual system and characterized by a visual percept that arguably appears to differ from reality. Illusions come in a wide variety; their categorization is difficult because the underlying cause is often not clear but a classification proposed by Richard Gregory is useful as an orientation. According to that, there are three main classes: physical, physiological, and cognitive illusions, and in each class there are four kinds: Ambiguities, distortions, paradoxes, and fictions.
MosaicA mosaic is a pattern or image made of small regular or irregular pieces of colored stone, glass or ceramic, held in place by plaster/mortar, and covering a surface. Mosaics are often used as floor and wall decoration, and were particularly popular in the Ancient Roman world. Mosaic today includes not just murals and pavements, but also artwork, hobby crafts, and industrial and construction forms. Mosaics have a long history, starting in Mesopotamia in the 3rd millennium BC.
Moorish architectureMoorish architecture is a style within Islamic architecture which developed in the western Islamic world, including al-Andalus (on the Iberian peninsula) and what is now Morocco, Algeria, and Tunisia (part of the Maghreb). Scholarly references on Islamic architecture often refer to this architectural tradition by a more geographic designation, such as architecture of the Islamic West or architecture of the Western Islamic lands. The use of the term "Moorish" comes from the historical Western European designation of the Muslim inhabitants of these regions as "Moors".
