Clerestory

In architecture, a clerestory (/ˈklɪərstɔːri/; lit. clear storey, also clearstory, clearstorey, or overstorey) is a high section of wall that contains windows above eye level. The purpose is to admit light, fresh air, or both.

Historically, clerestory denoted 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.

Similar structures have been used in transportation vehicles to provide additional lighting, ventilation, or headroom.

History

Ancient world

The technology of the clerestory appears to originate in the temples of ancient Egypt. The term "clerestory" is applicable to Egyptian temples, where the lighting of the hall of columns was obtained over the stone roofs of the adjoining aisles, through slits pierced in vertical slabs of stone. Clerestory appeared in Egypt at least as early as the Amarna period.

In the Minoan palaces of Crete such as Knossos, by contrast, lightwells were employed in addition to clerestories.