Cupola

In architecture, a cupola () is a relatively small, usually dome-like structure on top of a building often crowning a larger roof or dome. Cupolas often serve as a roof lantern to admit light and air or as a lookout. The word derives, via Italian, from lower Latin cupula (classical Latin cupella), from Ancient Greek κύπελλον (kúpellon) 'small cup' (Latin cupa), indicating a vault resembling an upside-down cup. The cylindrical drum underneath a larger cupola is called a tholobate.