Switzerland was neutral during World War II but extensive fortifications were built along its borders--especially with Germany. Built between 1937-1939, Fort Reuenthal sits on a high ridge overlooking the Rhine River and its purpose was to prevent the Germans from crossing the Rhine at the nearby hydroelectric plant. Above is one of four artillary blocks. Two were armed with 75 mm guns and two with machine guns.
Returning to the main tunnel I come across a volunteer who speaks impeccable English and ask him about the long side tunnel I just explored. This underground fortress was built by a contractor and when the military moved in they found a big flaw: if this fortification came under attack the only escape was via an opening right underneath one of the 75 mm guns--meaning you were exposed to enemy fire! So, the military ordered the contractor to build an escape tunnel (the one I just traversed). I explained to the volunteer my going down the tunnel twice due to the lights being off. He said they do that on purpose (turning the lights off) to discourage visitors from going further. "Why?", I ask. He answers, "people get claustrophobic down there". Boy he got that right! I recall when almost reaching the far end of the tunnel I nearly slipped on the wet floor and remember saying to myself how if I fell and broke a leg and started yelling-- nobody would hear me because I was so far underground and isolated.