Triforium

 Triforium:    A     **triforium**     is a shallow arched gallery within the thickness of inner wall, which stands above the   [|nave]   of a   [|church]   or   [|cathedral]. It may occur at the level of the  [|clerestory]   windows, or it may be located as a separate level below the clerestory. It may itself have an outer wall of glass rather than stone.

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