I love stone walls because they look like puzzles and you can see progress and strategy in every stone laid. You are right about the narrow street in Spain I expect the bulls to be coming around the corner at any moment. The wall from Dubai looks like it has petrified sponge that came from the bottom of the sea and the beautiful photo of the wall with the flowers needed a lot of little wedge stones to finish the job!
It's easy to build a brick wall. But for the stone one, you need a good eye, some imagination, and precision too.