Windows are a really ancient innovation, probably coincident with the growth of fixed and enclosed homes. Representations of windows happen in ancient wall paintings in Egypt and in reliefs from Assyria. The Egyptian examples reveal openings in house walls coated with mattings, such as the doors.
The devotion of the early Greeks to the home built around a courtled into an almost total disappearance of windows in their structure, because each room was lighted by a doorway to the central, colonnaded court. It’s obvious, moreover, the fantastic windows at the baths of Rome must have been enclosed in some manner, to be able to maintain the heat. The overall hypothesis is these terrific clerestory openings were filled, initially, with frames of bronze that subdivided the entire into small regions, each of which held a pane of glass. Generally speaking, however, glazed windows were rather unique in Roman times; marble, mica, and shell were often utilised to fill window openings.
Thus, it’s understood that the windows of Hagia Sophia in Constantinople (started 532) were full of pierced marble frames surrounding panes of glass. Islāmic mosque builders replicated this Byzantine technique of little pieces of glass inserted into a masonry framework and, by substituting cement for marble in the framework, obtained great freedom and richness in pattern layout, so that with using different colors of glass in the small openings, colorful effects were produced. Islāmic builders of Egypt and Syria also developed a very rich type of national window which was usually unglazed. This consisted of a projecting, bracketed, frame of timber with its sides completely filled by intricate grillwork shaped by carved, turned, wooden spindles. It wasn’t till the 12th and 13th centuries in northern and western Europe, however, this stained-glass technique reached its most distinguished improvement. Due to the softness of this guide, the cames could be molded into any pattern. Therefore, it was possible to decorate the windows of Gothic cathedrals with detailed pictorial layouts. Moreover, with the addition of stone mullions (slender vertical supports that form a branch between glazed areas) and a method of tracery in about 1250, church windows became progressively bigger.