While foreign leaders and their families walk the iconic restored sections of the Great Wall around Beijing, the ancient stones of a remote Ming-era stretch of the structure in northern central China have been sacrificed for cheaper dumping of coal-mining waste.For nearly 20 years, a section of the wall in Ningwu county, Shanxi province, was used as a short cut to dump slag, despite whistle-blowers repeatedly raising the alarm to officials, according to a report by Chinese state broadcaster...