Medallion (architecture)
A medallion or medaillon is a round or oval frame, which contains a plastic or pictorial decoration of a façade, an interior, a piece of furniture or equipment.
In the United Kingdom in the 19th century, this was a popular form of decoration in Neoclassical architecture. The frame and portrait were carved as one, in marble for interiors, and in stone for exterior walls.
It is also the name of a scene inset into a larger stained glass window.