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You may have noticed a similar structure just after the entrance of each tunnel, any ideas as to what it is? |
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You may have noticed a similar structure just after the entrance of each tunnel, any ideas as to what it is? |
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Answer: they were to act as shock obsorbers against outside explosive blasts. The direct tunnel route shown in black was filled with layers of lead, wood, stone to absorb the shock wave. The small tunnels around the main shaft allowed passage and reduced the shock with the perpendicular reflections. |