De architectura
In classical architecture, hypaethral describes an ancient temple with no roof. (From the Latin "hypaethrus", from Ancient Greek ὕπαιθρος "hupaithros" ὑπό hupo- "under" and αἰθήρ aither "sky, air".) It was described by the Roman architect Vitruvius in his treatise "De architectura", written for the emperor Caesar Augustus probably about 15 BC.