

Željava Air Base on the Croatia-Bosnia border is a relic of the Cold War, code-named Objekat 505. But it’s no longer top secret. Visitors can explore the abandoned concrete bunker concealed under Mount Plješevica, large enough to hide up to 60 warplanes. You can visit ruined buildings and even drive on one of the runways. Here’s a video of my visit:
Where is Željava Air Base?
Yugoslavia’s underground air base in Europe was strategically located on what is now the border of Croatia and Bosnia. It is about 150 km from Zagreb and 22 km from Plitvice Lakes National Park. Driving 18 km from Bihač on the Bosnian side, it was easy to find Željava Air Base by car. Google maps led me straight to the border checkpoint.
While other external EU border crossings can get quite busy, we were the only car passing through this one early on a weekday morning. You’ll need to stop at both the Bosnian and Croatian checkpoint windows. Have your passport or EU country ID card ready.
Stranger Danger: At the time of my 2024 visit, this was the external border of the EU. The wide open spaces are part of the Balkan smuggling route for illegal migrants. Border patrols in the area are likely to stop you if you try to enter the Željava Air Base from the Bosnia side without entering Croatia through the checkpoint.

Exploring the vast underground military air base will be the highlight of your visit. But first you have to find the bunker that is concealed under a mountain on the border of Bosnia and Croatia.
How to Get to Željava Air Base
From the border crossing, it was only a few kilometers drive on a pretty country road to reach Željava. It was hard to believe this peaceful landscape once concealed the nerve center for the air defenses of Yugoslavia.
GPS led us straight to a sign at the front entrance of Źeljava AirBase. There was no entrance fee to drive through the gate. Proceed at your own risk due to the landmines still in the area.

There’s a family-friendly photo-op near a snack bar and a parking lot. It reminds visitors to the Željava Air Base that the world-famous waterfalls of Plitvice National Park are only 22 kilometers away.
What to See at Željava Air Base
Before driving into the base, take a moment to explore the only remaining aircraft on the property, a C-47 transport where plenty of previous visitors have left their mark.
Driving straight through the entrance, stay on the paved road that passes abandoned buildings. You can still see what’s left of the toilets and an overturned troop transport bus.

An overturned troop transport in what’s left of the administrative buildings of Željava Air Base. You can explore the ruins, but stay in the paved areas due to landmines in the area.
Driving on the Runway of Željava Air Base
If you turn left from the entrance, you’ll reach the runway. Busy ground crews have kept it clear of weeds. Somehow, I get the feeling these guys know EXACTLY how fast a tractor can go on this former military landing strip.
As you’ll see in the video above, no one seems to mind if you give it a try with your car or motorcycle. Turn around and drive back toward Mount Plješevica for the highlight of your visit: exploring the abandoned underground military base.
Exploring Tito’s Secret Underground Air Base
While some of the tunnels are blocked with dirt and vegetation, you can’t miss the iconic main entrance to the bunker. You can imagine the MIG fighter jets driving through the notched opening to the 2.2 miles of tunnels in the underground hangar. Nowadays, it’s just a photo op.

Tourists outside the iconic entrance to the abandoned bunker at Željava Air Base. You can drive only a short distance inside before being blocked by debris. Bring a flashlight to explore deeper into the tunnels on foot. You’ll notice the remains of thick blast doors that were designed to withstand a nuclear bomb dropped from the outside but no match for the explosives that destroyed the base from the inside.

Make no mistake, walking deep into the darkness of this underground aircraft base can be dangerous. There is no natural light and flashlight beams get swallowed up in the vast black void. Sharp pieces of debris hang down and there are deep holes you can step into — as I found out the hard way. In this photo you can also see some of the mist filled with debris particles, probably asbestos. I’d recommend bringing an N-95 mask.

Leaving the bunker, it was a relief to step back out into the fresh country air. The tunnels are filled with flying debris particles and deep holes you might miss in the dark — even with a flashlight. After I injured my knee by falling into a hole and nearly lost my camera, we opted to put safety first and retrace our steps. I’m told you can visit the remains of the airbase control room if you venture farther with a guide.
History of Željava Air Base
Yugoslavia’s leader, Josip Broz Tito, split with Stalin in the aftermath of World War II. He feared a nuclear attack could come from the Soviet Union or the West. Construction started at Željava in 1948 and continued for 20 years at a cost of $6 billion — more than $42 billion in today’s US dollars.
The biggest underground military airport in Europe was designed to withstand a direct hit by a 20-kiloton nuclear bomb, like the one dropped on Nagasaki. The 2.2 miles of tunnels could shelter up to 1,000 people with food and water for a month. It housed the radar and strategic command for Yugoslavia’s air defenses. It was the hangar for dozens of Soviet-made MIG fighters.

A ray of sunshine shines through an entrance to Tito’s secret underground airfield on the Croatia-Bosnia border.
Destruction of Zeljava Air Base
Željava did not survive the Balkan Wars of the 1990s. Retreating Serbian forces blew it up from the inside, using an estimated 56 tons of explosives. The mighty Yugoslavian concrete shell withstood the blasts, but the contents were reduced to rubble.
In the wide open spaces outside the bunker, the EU is funding a landmine removal program. Explosives in the surrounding area have prevented attempts to develop the base as a tourist attraction or an airport for the nearby Bosnian city of Bihać.
Stranger Danger: Visitors should be careful to stay on the paved paths through the ruined buildings on the property, which the Croatian military uses to train bomb detection dogs.
Was there a Secret Yugoslavia Space Program at Željava Air Base?
A satirical documentary film called “Houston We Have a Problem” raised the possibility that Tito had a secret space program at Željava in the 1960s. Was it stolen by the Americans in their race to beat the Soviets to the moon? Watch the trailer for the film and decide for yourself.
Read more about Željava Air Base
I toured Željava Air Base with author Andrew Anžur Clement. His action-adventure novels follow Tito’s fictional secret daughter and her friends as they try to prevent the breakup of Yugoslavia. Download Tito’s Lost Children on Amazon or order the paperback books. You can also buy them at The House of Dreaming Books (Hisa Sanjajočih Knig) in Ljubljana.

Book covers of “Tito’s Lost Children” by Andrew Anzur Clement. In Book 2, his fictional characters get caught up in the real destruction of Željava Air base.
Where to stay near Željava Air Base
Zeljava was a great stop on our Bosnian road trip. Staying in the Bosnian town of Bihać, you’re a short drive away from the abandoned airbase and Plitvice Lakes just across the border in Croatia. The Muslim-majority town has a pretty riverfront park, some historic towers and a mosque. I can highly recommend the Motel Korzo on the main walking street and its upstairs Sofra restaurant for local food and a tasty breakfast.
We also visited the Strbacki Buk waterfall, but keep in mind that Google maps doesn’t always differentiate between paved highways and local goat paths; it just sends you by the shortest route. That’s how we ended up on the Croatian side of the waterfall and not in the park on the Bosnian side. Either way, it was beautiful. Keep your ID with you, just in case you have to cross the border unexpectedly.

Strbacki Buk is a spectacular waterfall on the Una River between Bosnia and Croatia. There was no admission charge to visit the less developed Croatian side but the Bosnian side is a park.
Other places to visit in the former Yugoslavia
If you like Cold War history, don’t miss Tito’s secret bomb shelter in Belgrade and the free Communist Tour of the Serbian capital. You’ll see where Tito is buried in the House of Flowers.
For a deeper dive into the Balkan Wars, visit Sarajevo to learn what people endured during the longest siege of modern times. You can also hike on the abandoned bobsled track from the 1984 Olympic Games. From Bosnia’s capital, you can take a day trip to the famous bridge at Mostar.
What to Bring to Zeljava Air Base
You’ll need a flashlight, sturdy walking/hiking shoes and a face mask to explore the bunker. It’s best to come by car. At the time of my visit there was no bus, but if you don’t want to drive you could sign up for a guided tour.
Croatia is part of the EU and the Eurozone, but Bosnia has not yet qualified for EU membership due in large part to its divided government with the Serb-majority Republika Srpska. The local currency is the Bosnian Mark (BAM), which you can get from local currency exchanges. But euros and even US dollars are widely accepted. Many mom-and-pop businesses don’t take credit cards. Younger people are likely to speak at least a little English.
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