Stretching from the shores of the Yellow Sea at Laolongtou in the east, curving around the top of Beijing and snaking across 5,500 miles of extreme terrain to Lop Nur, the Great Wall of China is undeniably an epic achievement of engineering and human endeavour.
Roughly tracing the southern boundary of the Mongolian steppe, traversing immense, lonely stretches of the Gobi Desert and rearing over exposed and steep sections of high savannah, the wall correctly occupies a special place in the imagination of our species as one of the wonders of the world.