In the 20th century, Switzerland — famous for its neutrality — became an alpine fortress, honeycombed with underground military installations. Behind this door hides an army hospital with several thousand beds.

Anticipating an invasion, Switzerland had airstrips buried in mountainsides and pop-up tank barriers embedded in freeways. Every strategic bridge and tunnel — designed with explosives built in — could be destroyed with a moment's notice.

My friend Fritz Hutmacher, who just finished 20 years in the army reserve, is giving away a few Swiss military secrets.

Rick: So, Switzerland is famous for being neutral?
Fritz: Yes. But over the last 70 years, the Alps got turned into a huge fortress. Now we have over 15,000 buildings like the ones around us with hidden guns. And even the neighbors they were not aware what was in, they were so secret.
Rick: Fifteen thousand underground installations?
Fritz: Yes.
Fritz: This barn looks like many others in Switzerland, but it hides a secret. Let's have a look inside.
Rick: Wow, look at this thing. What was this for? Why did they have this here?
Fritz: For World War II. It protected the fortress: the Alps.
Rick: And was it used later than World War II?
Fritz: Yes, it got updated over the last decades and has new technology in it.
Rick: So, actually, this gun works?
Fritz: This gun works.
Rick: Now, children could have grown up outside these doors and not known there was a gun was sitting here?
Fritz: Not only children. Generations were not aware what was actually inside these buildings.
Rick: And this is not wood. It looks like wood.
Fritz: No, that’s solid concrete.

In this town, four innocent-looking hay barns conceal a network of tunnels connecting several of these big guns. With the end of the Cold War, many of these once top-secret sites are now open to the public as museums.

Rick: This is the gun we just saw? Guten Tag. Kann ich spielen?
Swiss Man: Ja.
Rick: So, Fritz, from headquarters they would tell them what coordinates to set this on?
Fritz: Yes, they would put the coordinates into that calculator, and the gun gets adjusted.

A quick demonstration shows how the gun was prepped and loaded.

Rick: This is not just a museum piece — it feels like it could still work.
Fritz: Yes, if we had a live round, we could still fire it today.

And these wooden houses look cheery and vulnerable from the outside… but, like nearly all modern Swiss houses, Fritz's family home sits upon a no-nonsense concrete bomb shelter.

Fritz: This is the door to our bomb shelter.
Rick: Oh, man. How much must this weigh?
Fritz: A couple of thousand pounds — concrete and steel.
Rick: If you have a nuclear attack…
Both: You all run in here.

Swiss men are required to spend time in the military, including about 20 years in the reserve. And — like minutemen awaiting an invasion — they have their guns, gas masks, and ammo ready and waiting.

While the Swiss may be ready for war, they seem most at peace with nature.

Boats connect towns around Lake Lucerne. That’s its English name, but the Swiss call it the Vierwaldstättersee — literally, “Lake of the Four Forest Cantons.” That’s because it lies at the intersection of four of Switzerland’s cantons or states. Romantics will want to ride one of the classic paddleboat steamers. A short ride drops you at any number of interesting sights — one of which come with a surprise.

Imagine it’s 1941. You’re Swiss; your country is completely surrounded by Hitler and Mussolini. The Nazis are on the move. What to do? [knock, knock] Turn your mountains into a hidden fortress.

The Swiss managed to make their rugged mountains an even more effective barrier. How? By lots of strategic tunneling.

One example, the Fortress Fürigen has done its duty. Recently decommissioned, it now welcomes visitors interested in Switzerland’s secret defenses.

Guide: In central Switzerland we have now nine forts like this, bigger ones and smaller ones. There are installed I think in total 44 canons.

The Swiss implemented a plan to retreat into the mountainous heart of the country and defend themselves with a series of hidden fortresses dug into mountain sides like this one.

Guide: Here we enter into bunker #2. You see here the canon. You can turn it, the elevation…
Rick: I can sit here on the gun. Can I sit on this?
Guide: Yeah you can.
Rick: Push this down? 62—
Guide: Fine, yeah.
Rick: And then I go, I want to go to 21.
Guide: Fine, yes.
Rick: Wow there it is, 62 21, the top of the peak.
Guide: Fire [laugh].

With the advent of the Cold War in the 1950s, the fortress was retooled for the threat of the USSR. The Swiss have since found documents indicating that both the Nazis and the Soviets actually had plans to invade Switzerland.

Guide: This is the bedroom for 100 soldiers; 50 beds, they have to share it because they have to work in shifts. This is the dining room and over here the kitchen. And all these rooms and other forts have been built for survival of Switzerland. Hitler took Belgium, Netherlands and we had the feeling we are next.

Wandering through this hidden fortress you’re reminded how perilous Switzerland’s position was in the 20th century and how committed the Swiss were to defending their freedom.