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.