A search for an underground escape route said to have been used by Al Capone. Also: who or what built earthen mounds in Washington state.
Ended
Secrets of the Underground
February 14, 2017
December 16, 2017
2
16
English
Millions of dollars of stolen Gold Rush treasure is rumored to have been stashed in a cave in Northern California. Rob Nelson and Stefan Burns use cutting-edge technology to search for the legendary treasure.
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