The decorative oval shield often used in Baroque architecture is a cartouche.
A cartouche is an ornamental frame, usually oval or oblong and slightly convex, that holds an inscription, coat of arms, painted scene, emblem, or low-relief design. Its edges are often shaped with scrolls, folds, pierced forms, or other elaborate ornament. This combination of a framed centre and animated decoration made it especially suitable for Baroque façades and interiors.
The architectural cartouche developed from Renaissance ornament and became increasingly common during the Baroque and Rococo periods. It could appear above a doorway, within a pediment, on a façade, or in a ceiling scheme. Sometimes it carried practical information such as a date or motto; in other cases, the frame itself was the principal decorative feature.
The term can cause confusion because “cartouche” also describes the elongated border surrounding a pharaoh's name in Egyptian hieroglyphics. The architectural object is related by its enclosing function but is not limited to Egyptian monuments. A keystone is the central wedge of an arch, a finial is a crowning ornament, and a pediment is the gable-like element above a classical façade.