An old fence in a backyard is helpful for privacy but the wall can be rather bare and boring. Its possible to take that old fence and easily turn it into a conversation piece.
The birdhouse idea is one I would use but I would add a few vining plants with the houses to add interest and flowing lines. The following you tube show how easy and fast a wall can be decorated.
Birdhouse can be picked up at sales for a dollar or so. They can also be easily made and would make a great family project.
This project will only take a few hours and can use whatever materials you have on hand. I have seen mirrors, old farm equipment, tools, gourds, masks, etc…
Another idea for an old wall is using collectibles on the wall but adding a vertical garden along the fence. It will soften the fence and add depth to the yard. Another advantage is homegrown chemical free produce.