Secret Underground
- Episode aired May 17, 2014
- TV-PG
- 42m
Americans may be aware of what's above ground, but do they know what's concealed beneath? And could subterranean facilities on U.S. soil house secrets so dangerous, our government would stop... Read allAmericans may be aware of what's above ground, but do they know what's concealed beneath? And could subterranean facilities on U.S. soil house secrets so dangerous, our government would stop at nothing to keep them hidden? We examine the tunnels, cities, and fortresses covertly c... Read allAmericans may be aware of what's above ground, but do they know what's concealed beneath? And could subterranean facilities on U.S. soil house secrets so dangerous, our government would stop at nothing to keep them hidden? We examine the tunnels, cities, and fortresses covertly constructed beneath the feet of the American public.