Here's the process shown of a painting of a old style door. I painted it on a 6' x 4' canvas to hang in front of a window. The canvas was originally intended to cover my roommate's room, so the room can be darker during the day. He asked me to paint a door with fake perspective so it looks like a secret door. It took me two weekends of on and off painting to compete.
Line work and underpainting.
Work on the stone and iron rods