Season 3 Episodes10
Cast2
Barry Aird
Narrator (voice)
Jonathan Adams
Narrator (voice)
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6.8
Secret Underground
6.8/10 · 38 votesMay 17, 201460 min
Ranked #9 of 10 in Season 3•−0.4 vs season avg
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 at nothing to keep them hidden? We examine the tunnels, cities, and fortresses covertly constructed
Seasons4
Episode Summary
"Secret Underground" is episode 8 of America's Book of Secrets season 3. It scored 6.8/10 from 38 votes, ranking #9 of 10 episodes this season (season average 7.2). It aired on May 17, 2014.