Earlier in the year I had stood on the most easterly tip of the Great Wall at Lao Long Tou or Old Dragon Head. Today I would stand on a restored section of the most westerly extremity the Wall. Thousands of kilometres separated these points – one beside the sea and the other in the desert. The Wall once extended beyond this point but the crumbling Xuanbi Changcheng or Overhanging Great Wall believed to have been built in 1539 is ...