An oculus is a circular opening in the center of a dome or in a wall. Originating in antiquity, it is a feature of Byzantine and Neoclassical architecture. It is also known as an œil-de-bœuf from the French, or simply a "bull's-eye".

Louis XVI style, also called Louis Seize, is a style of architecture, furniture, decoration and art which developed in France during the 19-year reign of Louis XVI (1774–1792), just before the French Revolution. It saw the final phase of the Baroque style as well as the birth of French Neoclassicism. The style was a reaction against the elaborate ornament of the preceding Baroque period. It was inspired in part by the discoveries of Ancient Roman paintings, sculpture and architecture in Herculaneum and Pompeii. Its features included the straight column, the simplicity of the post-and-lintel, the architrave of the Greek temple. It also expressed the Rousseau-inspired values of returning to nature and the view of nature as an idealized and wild but still orderly and inherently worthy model for the arts to follow.