Our sole surviving Ancient Roman writer on Architecture, Vitruvius, condemned the prevailing style of Wall Painting as it depicted buildings which could not exist in the actual three dimensional world:
"because similar forms never did, do, nor can exist in nature. These new fashions have so much prevailed, that for want of competent judges, true art is little esteemed. How is it possible for a reed to support a roof, or a candelabrum to bear a house with the ornaments on its roof, or a small and pliant stalk to carry a sitting figure; or, that half figures and flowers at the same time should spring out of roots and stalks? And yet the public, so far from discouraging these falsehoods, are delighted with them, not for a moment considering whether such things could exist." - Book VII, Chapter 5, Section 4
And yet, these paintings of an apparently fanciful architecture were scrupulous reproductions of ancient paintings documenting the wooden stage sets of the fifth-century B.C. Athenian Dramas, such as those of of Sophocles and Euripides.
Here we see the left wing of a stage, in form derived from Temple architecture, but realized in wood, and attenuated in form, thus distancing itself from the "real". And here we also see the characteristic ornaments of the Doric and Ionic manners together, enclosing a volume three dimensionally rendered within which the actors are depicted: all this easily imagined as also rendered in contemporary low relief.
Thus a sanctuary architecture evokes the setting of the principal places of these ancient dramas, shrines and palaces.
We see all this fully realized in the Painting found in the House of Augustus. The stage frames a central painting, depicting an outdoor sanctuary. The foreground can be read as a tripartite Stoa, opening out, in its centre, toward a sacred grove, its out of the everyday world aspect signaled by elongated proportions, with ornamental Theatrical Masks on the parapets. And the doors, on stage-left and right stand, ready to reveal the actors of our play, perhaps Sophocles' Oedipus at Colonus.
The primary life experiences of our Roman writer, Vitruvius, is illuminating. He spent the better part of his life as an artillery engineer in the Legions of Julius Caesar and Augustus, working with wood, metal and rope to construct machines: catapults and wall shattering crossbows. He was thus predisposed to construction, to what woks, to the real of a practical man. The Real of the Iconic, the Symbolic, which most of his everyday contemporaries delighted in, was sadly closed to him.
Roman ornamental Wall Painting reveals but one artistic expression of Ancient Greek Drama. It also informed Greek Pedimental Sculpture - see below for an excerpt exploring these ideas, or you can listen to the full lecture here.