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A coffer 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. The stone coffers of the ancient Greeks and Romans are the earliest surviving examples.A, from Palmyra; B, Basilica of Constantine.

Roman Ceiling Panels

A coffer in architecture, is a sunken panel in the shape of a square, rectangle, or octagon in a ceiling,…

"The Pont-y-ru-Prydd goes over the River Taff near Newbridge. The arch measures 140 feet between the abutments, and has a rise or versed sine of 35 feet. The width of the soffit is 15 feet 10 inches at the springing, diminishing to 14 feet 5 inches at the crown by six offsers." — Encyclopedia Britanica, 1893

Pont-y-tu-Prydd

"The Pont-y-ru-Prydd goes over the River Taff near Newbridge. The arch measures 140 feet between the…