地下的美国人：一战秘密城市 Americans Underground: Secret City of WWI (2017)认领

　　An amazing discovery has been made beneath a farm field in Northern France: a vast underground city where World War I soldiers, on both sides of the conflict, took refuge a century ago. Even more remarkable, it is one of hundreds of buried havens set up close to a 45-mile stretch of the Western Front. Follow American explorer and photographer Jeff Gusky as he documents one of t...