cupola

In architecture, a cupola is a small, most-often dome-like structure, on top of a building. Often used to provide a lookout or to admit light and air, it usually crowns a larger roof or dome. The word derives, via Italian, from the lower Latin cupula (classical Latincupella from the Greek kypellon) small cup (lat. cupa) indicating a vault resembling an upside down cup. Cupolas often appear as small buildings in their own right. They often serve as a belfry, lantern, or belvedere above a main roof. In other cases they may crown a tower, spire, or turret. The chhatri, seen in Indian architecture, fits the definition of a cupola when it is used atop a larger structure.