A squinch in the palace of Ardeshir, near Firouzabad, Iran. Sassanid period.

A squinch in architecture is a piece of construction used for filling in the upper angles of a square room so as to form a proper base to receive an octagonal or spherical dome. Regular octagons A regular octagon is an octagon whose sides are all the same length and whose internal angles are all the same size "Globose" redirects here See also Globose nucleus. A sphere (from Greek σφαίρα - sphaira, "globe A dome is a common structural element of Architecture that resembles the hollow upper half of a Sphere. It was the primitive solution of this problem, the perfected one being eventually provided by the pendentive. A pendentive is a constructive device permitting the placing of a circular Dome over a square room or an elliptical Dome over a rectangular room Squinches may be formed by masonry built out from the angle in corbelled courses, by filling the corner with a vise placed diagonally, or by building an arch or a number of corbelled arches diagonally across the corner. In Architecture a corbel (or console) is a piece of stone jutting out of a wall to carry any superincumbent weight

In Islamic architecture, especially in Persia, where it may have been invented, the squinch took the form of a succession of corbelled stalactite-like structures known as muqarnas. Islamic architecture has encompassed a wide range of both secular and religious styles from the foundation of Islam to the present day influencing the design and construction The Persian Empire was a series of Iranian empires that ruled over the Iranian plateau, the original Persian homeland and beyond in Western Asia A stalactite ( Greek stalaktites, (Σταλακτίτης from the word for "drip" and meaning "that which drips" is a type of Speleothem Muqarnas (Arabic مقرنص is a type of Corbel used as a decorative device in traditional Islamic and It was also commonly used in the early churches of Europe and the East.