WWII bunker time capsule hides under Paris train platforms

It's a time capsule passed over unknowingly each day by passengers at Paris's Gare de l'Est train station: a bunker built between the First and Second World Wars hiding under a trap door. Every French train station has one of the secret shelters, which were meant to enable rail workers to continue to regulate train traffic during an attack from the air. The bunkers are all linked by a phone system, and hermetically sealed to protect against poison gas.