Clerestory (; lit. clear storey, also clearstory, clearstorey, or overstorey)'s an architectural term denoting an upper level of a Roman basilica or of the nave of a Romanesque or Gothic church, the walls of which rise above the rooflines of the lower aisles and are pierced with windows. The purpose of the clerestory's to give light to the inner space of a large building. History Ancient world The technology of the clerestory appears to originate in the temples of Egypt. The term "clerestory"'s… (More on Clerestory)