Dong Yao-hui, Wu De-yu and Zhang Yuan-hua were the first men to walk the entire length of the Ming Dynasty Great Wall. After two years of preparation, they embarked on the epic trek that they thought would take them three years, but would in fact be completed in just 508 days.
A walk of 17 months and 8,850 kilometers (5,500 miles) that would test their endurance, but also take them into the record books as the first people ever to walk the length of the wall