Hypaethros, or hypaethral opening is the Greek term quoted by Vitruvius (iii. 2) for the opening in the middle of the roof of decastyle temples, an example being found in Athens in the temple of Jupiter Olympius, which is octostyle. There was no example in Rome. However at the time Vitruvius wrote (c. 25 AD) the cella of this temple was unroofed, ...