Tunnels have been used throughout history, as a means of travel and at times, safety..
I read about those tunnels under D.C.. interesting.
Cold War Civil Defense Museum- Greenbriar Virtual Tour
tanvil, in-case of war, take your family too that place.
Built the whole damn thing without the sheep knowing, like ak9 is saying.
The rats in D.C. were going to hide in there till things were safe. Leaving us sheep outside to fend for ourselves.
But don't you dare become a prepper, our Govt. does not like you.