the implied subject of "looking down into a valley"

Human beings like a prospect from which they can survey a landscape, and at the same time they enjoy a sense of refuge. A cave on the side of a mountain, a child’s tree house, and the king’s castle are situations with appeal. Protection afforded by an overhang of some sort (trees, cliff face, roof) is preferred, along with a sense of being “safe” from observation or attack from behind. The most attractive landscapes tend to combine some of these elements, in pictures as much as in reality. In fact, most landscape representation in the history of painting places the implied viewer at some desirable vantage point — a cliff edge, perhaps, typically looking down into a valley.

Q. I was wondering what would be looking down into a valley. Would the implied subject of “looking down ~” be the “implied viewer” or the “vantage point”, which rephrased as a cliff edge in this sentence?