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- Season 1 1993-12-10
- Season 2 1994-12-16
- Season 3 1995-08-20
- Season 4 1996-09-02
- Season 5 1997-08-17
- Season 6 1998-07-27
- Season 7 2000-01-03
- Season 8 2001-01-08
- Season 9 2002-01-02
- Season 10 2003-01-01
- Season 11 2004-01-16
- Season 12 2005-01-05
- Season 13 2006-01-04
- Season 14 2007-01-17
- Season 15 2008-01-07
- Season 16 2010-01-14
- Season 17 2010-10-29
- Season 18 2011-10-03
- Season 19 2013-07-16
- Season 20 2021-02-20
- Season 21 2021-07-25
- Season 22 2021-11-28
- Season 23 2022-02-16
Season 23 Episode
- Season 17 Mega Stores
- Season 17 Supersized Food
- Season 17 Coin Operated II
- Season 17 Engineering Disasters 22
- Season 17 Dogs
- Season 17 Built to Last
- Season 17 Secret Underground
- Season 17 Made in the USA
- Season 17 Driver's Seat
- Season 17 Rice
- Season 17 Packaging
- Season 17 Grease
- Season 17 Ropes & Chains
- Season 17 American Trucking
Modern Marvels - Season 17 Episode 7 Secret Underground
7.90 44 minutes Just below the surface, there's a whole different America hidden from public view. Take a revealing look at the America under our feet, from secret military installations, and experimental farms to tunnel networks and neutron lasers.
