Clerestory

In architecture, a clerestory (/ˈklɪərstɔːri/ KLEER-stor-ee; lit. 'clear storey', also clearstory, clearstorey, or overstorey; from Old French cler estor) is a high section of wall that contains windows above eye-level. Its purpose is to admit light, fresh air, or both.

Historically, a clerestory formed 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 which are pierced with windows.

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