You might think I have some grand reason for painting the back wall at this stage. No. Sorry to disappoint you. I am tired of being lost in the maze of columns and thought if I painted the light at the end of the "tunnel" I might see the light at the end of the tunnel.
Painting the back wall and adding the base for the left columns has helped give me some direction. The left columns are now complete except for the highlights. Working on the lower part of the right wall begins to give a greater dimension to the perspective.