A pretty ordinary barn by most standards....except years ago, probably the roof before this one,
I had the pleasure of replacing the metal pieces of roofing next to and over the peak of the hay mow barn door.
Each sheet was 30" wide. I sat on a wooden ladder that was simply "hooked" over the ridge to the other side of the upper roof...dangling if you will. The ladder reached from the ridge to a little below the upper roof's eve, and was just a few inches from the edge of the front of the barn. I then had to pull the sheets with a rope up from the ground where Dad had cut them, slide them across my body, then hold them and nail them onto not too solid of framing. Let me tell you....it was a long way down to the ground...

The next image gives a larger view...