Hidden Beneath the Cities
Crystal Cathedrals and Buried Bunkers
Season 1 Episode 2
Poland's salt mine, a Cold War bunker, an ancient Egyptian site, and China's mysterious Longyou Caves.
Hidden Beneath the Cities airs on National Geographic Channel HD at 3:00 PM, Thursday 3 September. (Subtitles.)
Topics
News ➝ Current Affairs
Documentary