Cupola

In architecture, a cupola (/ˈk(j)uːpələ/)[1] is a relatively small, usually dome-like structure on top of a building[2] often crowning a larger roof or dome.

[citation needed] The chhatri, seen in Indian architecture, fits the definition of a cupola when it is used atop a larger structure.

The square, dome-like segment of a North American railroad train caboose that contains the second-level or "angel" seats is also called a cupola.

[7][8] The term cupola can also refer to the protrusions atop an armoured fighting vehicle due to their distinctive dome-like appearance.

They allow crew or personnel to observe, offering very good all round vision,[9] or even field weaponry, without being exposed to incoming fire.