Roof lantern in the context of "Florence Baptistery"

A dome (from Latin domus) is an architectural element similar to the hollow upper half of a sphere. There is significant overlap with the term cupola, which may also refer to a dome or a structure on top of a dome. The precise definition of a dome has been a matter of controversy and there are a wide variety of forms and specialized terms to describe them.

A dome can rest directly upon a rotunda wall, a drum, or a system of squinches or pendentives used to accommodate the transition in shape from a rectangular or square space to the round or polygonal base of the dome. The dome's apex may be closed or may be open in the form of an oculus, which may itself be covered with a roof lantern and cupola.

A window is an opening in a wall, door, roof, or vehicle that allows the exchange of light and may also allow the passage of sound and sometimes air. Modern windows are usually glazed or covered in some other transparent or translucent material, a sash set in a frame in the opening; the sash and frame are also referred to as a window. Many glazed windows may be opened, to allow ventilation, or closed to exclude inclement weather. Windows may have a latch or similar mechanism to lock the window shut or to hold it open by various amounts.

Types include the eyebrow window, fixed windows, hexagonal windows, single-hung, and double-hung sash windows, horizontal sliding sash windows, casement windows, awning windows, hopper windows, tilt, and slide windows (often door-sized), tilt and turn windows, transom windows, sidelight windows, jalousie or louvered windows, clerestory windows, lancet windows, skylights, roof windows, roof lanterns, bay windows, oriel windows, thermal, or Diocletian, windows, picture windows, rose windows, emergency exit windows, stained glass windows, French windows, panel windows, double/triple-paned windows, and witch windows.

In architecture, a cupola (/ˈk(j)uːpələ/) 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 United States Capitol features a dome situated above its rotunda. The dome is 288 feet (88 m) in height and 96 feet (29 m) in diameter. Designed by Thomas U. Walter, the fourth Architect of the Capitol, it was constructed between 1855 and 1866 at a cost of $1,047,291 (equivalent to $17.6 million in 2024). The Statue of Freedom tops the lantern on the dome, and the dome is centered over the origin on street maps of Washington, D.C.

The dome is not stone, but rather cast iron carefully painted to appear to be made of the same stone as the capitol building below. It is actually two domes, one inside the other, and the total weight is 9.1 million pounds (4,100 t). The dome's cast iron frame was supplied and constructed by the iron foundry Janes, Fowler, Kirtland & Co. in the Bronx, New York. The interior of the dome includes a detailed geometric and floral pattern of lightly colored plasterwork, with Constantino Brumidi's monumental ceiling fresco, The Apotheosis of Washington, appearing in the oculus at the top of the inner dome.