In my opinion, the best-designed walls are those found in Peru, specifically in Cuzco and Machu Picchu. The Inca Empire has been known for constructing one of the most solid and resistant walls in history.
The Inca civilization is well known for its advanced masonry work, much of which can still be seen today in Machu Picchu and Cuzco in Peru. Their large dry stone walls display huge blocks that had been carefully cut to fit together tightly without mortar and with levels of precision unmatched anywhere else in the world.
The stones are so closely spaced that a single piece of paper will not fit between many of the stones.
This precision, combined with the rounded corners of the blocks, the variety of their interlocking shapes, and the way the walls lean inward have puzzled scientists for decades. The method used to match precisely the shape of a stone with the adjacent stones is still unknown.
This wall in Cuzco shows the perfect shape of a puma. On the right, you can see me smiling at the camera.