Walls are also Spaces
Walls have texture, weathering, and color. Walls can have forms, like windows, doors, signs, and characters. That is already inspiring enough to paint them. Walls build rooms and those rooms will be embedded in natural light. From there shadows, overlaps and passages arise. They have edges on which I can wonderfully observe how things have a light and a shaded side. Where you can see works with scaffolding it becomes extremely interesting. You look inside and are discovering something new during the process.
It has a metaphorical component as well.