Biking through a WW1 tunnel carved into the Swiss Alps

This tunnel was built in world war 1 and has a place for a small artillery crew and even has a “Sprengstelle” (explosive point) for destroying the passage if needed. There are a few of these hidden bunkers in Switzerland: Over 20,000 hidden military bunkers and hundreds of secret tunnels dug into its mountains. It was all part of a Cold War “National Redoubt” defense plan.