altarpiece

From altar +‎ piece.

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altarpiece

Wikipedia

altarpiece (plural altarpieces)

1. a work of art suspended above and behind an altar in a church
   • 2008 December 15, David Samuels, “Atomic John: A truck driver uncovers secrets about the first nuclear bombs”, in The New Yorker‎^[1]:

     I walked across the concrete to examine the altarpiece of the atomic age. A large crack ran through it.