"The Germans built the bunkers according to absolutely standard patterns, so we can walk into one and know straight away where everything will be - the hole for the radio mast, another for the periscope, the air vents, the sleeping area and so on, " said amateur archaeologist Jean-Francois Laquieze.

BBC: Hitler's Atlantic Wall: Should France preserve it?

"If the treatment wasn't complex, there wouldn't be such a high number of suicides amongst ex-servicemen, and so many in prison and sleeping on the streets, " he argued.

BBC: Conservatives' debate

Poor sleeping patterns are both a symptom of bipolar disorder and can bring the illness on, so learning good sleep hygiene is especially important for young people at genetic risk for the disease.

CNN: Can a person 'discourage' bipolar disorder?

There are hooks on one wall to hang a sleeping bag and a spot on the opposite wall for a fold-down table and foot restraints so astronauts can use a laptop computer.

BBC: A space of one's own

So, in one corner you have the Occupiers, sleeping out on the streets, and sometimes getting pepper sprayed.

FORBES: Wall Street Has Been Entitled, NOT Occupy Wall Street