A coffer (or coffering) in architecture, is a sunken panel in the shape of a square, rectangle, or octagon in a ceiling, soffit or vault. A series of these sunken panels were used as decoration for a ceiling or a vault, also called caissons ('boxes""), or lacunaria (""spaces, openings""), so that a coffered ceiling can be called a lacunar ceiling: the strength of the structure is in the framework of the coffers. The stone coffers of the ancient Greeks and Romans are the earliest surviving examples, but a seventh-century BCE Etruscan chamber tomb in the necropolis of San Giuliano, which is cut in soft tufa-like stone reproduces a ceiling with beams and cross-beams lying on them, with flat panels fillings the lacunae.