
Zeljava Air Base Underground – Yugoslav Secret
What to expect, how to get there. Zeljava Air Base visit – Objekat 505
The Background
The main reason for heading up to the Plitvička National Park again (Jajce Jezero), was not this time to visit those beautiful lakes, which bring most tourists to the area.
My research for interesting things to see on our travels caused me to stumble upon the abandoned top-secret airbase at Željava. Some of which is on the Croatian side, the rest spans the border of Bosnia and Herzegovina. We were going to have a look around.
Having seen the lakes and tourist crowds a year ago, we decided to forego the experience again.
Zeljava Air Base Objekat 505
- What to expect, how to get there. Zeljava Air Base visit – Objekat 505
- Highly Recommended Activities
- Highly Recommended – Zeljava Air Base Tour
- Zeljava History – Objekat 505
- Zeljava Air Base Visit
- Željava Air Base Photos – Objekat 505
- Zeljava History and Operational Summary
- How to Get to Željava – Objekat 505
- Željava Air Base Plan and Map
- Essential Travel Toolkit
- References / More Information
Highly Recommended Activities
We planned the day such that the bio-in-laws, would disappear in the morning to the lakes, Cassie was desperate to join them so went to show them around. Then if they returned in time they would join Wendy and myself to visit Željava to try and find the secret base! As it goes they did return and three of us disappeared to find the base. Cassie stayed at camp with Carole.
We had spent the morning tidying up the car and catching up on what would be best described as administrative tasks. Oh, I also spent the morning superglue’ing the rear indicator lens back together, from two million pieces in the grass…


From our campsite across the valley, we could see Mount Plitvička and Mount Gola which hid Zeljava from us, the summit is home to modern radio masts, probably cellular these days.
Being overlooked by this helped build up the anticipation for me, we had been longing to do something different since Mont Saccarel in Italy. We don’t like to do what the normal tourist crowd does!
We did not manage to get to the top of the hill to explore, although I had a GPS track to find our way. I believe during the period that the base was in use, the mountain over the airbase housed a radar warning system which was part of a network for Yugoslavia, this formed an early warning system for the airspace around Yugoslavia similar to NORAD.
Regardless of what was now at the top, it would have been nice to explore, and it probably would have provided great views of the base, back to the camp and also over Bosnia and Herzegovina.

On the net, there is a lot of interest in military bases and sites, and Zeljava is no different. It did not take long to establish its location months before we departed the UK. I did have to do a bit of detective work though.
I used Google Earth to verify and then generated a waypoint for the GPS. As I also had 1:200k maps of the area from our last visit, I drew a box around the area and highlighted it so I could find it during the trip.
Before we departed the UK, I had been to Stanford Maps in London looking for more detailed maps, I would have preferred 1:50k or 1:25k, but they had nothing better than I had. I also had a look on the Internet for a source but was not successful, I don’t know if such detailed maps are produced for the area. Perhaps not for walkers, I guess the land mine risk is still very real, I expect military maps do exist thou, in fact, I have seen extracts of Military maps, so am sure they exist, but not how to get them.
If you know a source of maps please leave a comment or something.

Getting to the Plitvička area had been a great drive the previous day, although it was slow. I set the GPS to go via a couple of minor towns along the border area, and also set it to minor and unpaved roads, avoiding highways and major roads. Hoping to stay off the main drags and in areas of interest.

Oh how the route impressed us, we went through tiny habitations and along mostly single carrage roads were the Tarmac barely remained. One section saw us follow about 20 km along a gravel route to a lake, I think the people there before us had stayed the night, it was a watering hole for a horse trek also.
Had we been on our own I think we would have stayed the night. At the exit of this track, we took the opportunity to stop at a sign that said “Med”, which is honey.

The locals sell their honey, local plum brandy known as Rijeka and often wine, being tourists, they took the opportunity to sell us the golden delight at a much-inflated rate, not speaking Croatian meant we had little choice, but to either accept or move on. Needless to say, we choose the former, two gigantic jars of Honey for 150 Kuna. Working out the price I have no idea how we got to it, when we did not understand the man, he just shouted louder! Our indications to write it in the dirt got lost in translation. Oh well, we leave richer.

Later on, the route took us along routes that overlooked Bosnia and Herzegovina, where we could see old border walls from the conflict, deserted habitations and bullet-ridden houses, signs for mines are still a fairly common sight and leave otherwise beautiful land abandoned.
Croatia has always struck me as a country of contrast, in respect to redevelopment post-conflict. The coast is very built up and apparently affluent, whereas if you head inland, there are still areas where buildings are derelict and bare the bullet scars of the war. The people on the coast are mostly involved in some way with tourism, the people inland are hard-working farmers and manual workers. They look honest and interesting, I wish I could converse with them.
Highly Recommended – Zeljava Air Base Tour
Zeljava History – Objekat 505
Thanks to the net there is a lot of information available about the history of the base. Its construction started around 1948, at the time it was known as Objekat 505. The actual pouring of the concrete is in some of the info I read is supposed to have started a few years later in the 50’s. Construction was finished around 1968. On completion it was given the name “Klek” and had a military post cost of 4868, to reflect the start and finish years.

The design of the base is such that the tunnels are semicircular and big enough to allow fighter jets to enter, the tunnels are about two jets wide. When the tunnels were constructed they had positions for explosives to be placed, such that detonation would cause the facility to become unusable. The entrance to the tunnel is shaped to allow the tail of the aircraft to enter the tunnel like an upside down “T” shape, these could be blocked by 1-meter thick pressurised doors.
The internal sections of the base are designed to withstand a 20 kilo-tonne nuclear bomb. Which I have read is equivalent to the Nagashima bomb, in Japan during World War Two. As you would expect being able to withstand such a blast would imply that the doors would have to be kept shut. The base internally had generators, fuel storage, waste storage and water. The most important facilities were all located in the tunnels, with a mess room capable of seating 1000 people. Fuel was piped from storage tanks located 10 to 20 km away in a mountain in Bosnia.
Above the main tunnels in the mountain, accessed by an elevator only from inside the tunnels, was a room that was used for strategic planning and by the operators of the early warning radar system.
The base was in use until the 1990s and at one stage was looked at with a view to modernisation around the late 1970s. When it was first built it is said to have cost some where between 4 and 6 billion US dollars. Apparently the funding came from the World Bank and was secured for development of communication routes (motorways and roads) in the former Yugoslavia. The construction was carried out by a Serbian firm.
In the end, during the conflict, it was the Yugoslav Peoples Army (JNA) who detonated the pre-prepared explosives for the destruction of the base on their retreat. I guess the base would have been rather useful to advancing forces. Later there was further distraction of the base using 56 tonnes of explosives, by the military of Serbian Krajina, this was carried out in 1995. Articles on the website locals say that the force shocked local towns like an earthquake and that the tunnels smoked for 6 months.

External to the tunnels there are five runways on the base three lead straight into tunnels. The last two were used for other aircraft to land. The total area I’d the base was on the order of 9km by 4km.
Ordinarily, staff at the base lived in the town of Bihać, which is in Bosnia now, this was the nearest city. I have read on one site that there was a dedicated bus service between Bihać and the base for staff to commute.
Zeljava Air Base Visit
From the Croatian side of the airbase coming from the Plitvička national Park, there is only really one way to get to the base by road. In order to do this, your arrival is via the small village of Zeljava, which seems almost empty save for a few dozen people who live in the houses.
Between the village and the base are various buildings that appear to be abandoned almost derelict in some cases. Shortly after the village on the main road on the left you pass gates, behind which it is possible to glimpse an old military plane. It is possible to see how cars have avoided the closed gates and damaged fence, to make their own path to the road behind the gates. Where it eventually leads who knows.
We continued past the planes to find the rest of the base, about 1 kilometre further, we came across what was our first sign of more to be seen. Buildings are hidden on the right by trees, this time of the year the dense trees and shrubs provide good cover for the buildings and relics hidden around the base. We cut off the main approach road, to explore what appear to be vehicle maintenance or facility areas. We abandoned the car at this stage choosing instead to explore by foot.
Proceeding towards the runway areas southeast from where we were brought us via vehicle inspection ramps to another open area, that we were not sure of the use of, but it was littered with hydraulic hoses and metal scraps, there were various bullet-ridden sign posts and behind the trees, what looked like a discarded bomb, that was not / had not detonated.
We continued towards the end of what was runway 4 and runway 3, which meet at what looks like an apron, prior to the entrances to the tunnels 1 & 2. Turning right, past another mine warning, the open apron gives way to the approach to the tunnels, which was almost claustrophobic with the tree cover that was slowly reclaiming the base, making it feel close. As you approach the tunnel entrance you feel that there is something watching you. All the time listening to rustling and noises in the trees, never being able to identify what the source was. Eventually, we knew we were close by the wall of cold air that hit us, emerging from the tunnels.

Shortly before the tunnel entrance, we noticed a strange metal object that although half complete looks like a soldier or guard’s metal hat.
The tunnel mouth although visible is obscured on the lower half by a mount of dirt that has been placed to prevent people from taking vehicles into the tunnels. Entrance by foot is possible, but having no torches or breathing equipment we choose to avoid this option on this occasion, instead staring into the dim light. We chose to avoid entrance because of a report I had read warning of toxic chemicals in the dust and potentially radioactive waste from the fire detection equipment that was unaccounted for. Apart from this entry is fairly hazardous due to the unstable nature, but probably would not have prevented us if we had not been fortunate enough to read the report (available in the site links below)
After this, we went on to explore tunnel entrance two, but were interrupted by the sudden noise of several 4×4’s at first we were unsure of the nature of these vehicles, as I had previously read of border police being sensitive in this area, probably because of the unguarded border to Bosnia and Herzegovina. Luckily the vehicles turned out to be civilian tourists. With this, we recovered our vehicle.

We returned back with the vehicle to explore the remaining section beyond the apron towards the unmanned Bosnian border, along the approach we passed various buildings for fire and parking areas. In one area, we came across the remains of a military vehicle minus the chassis and engine on its side. This looked like it had been hit by something, judging by the holes in the body. Not sure what it was used for thou. Along the road, we came across spent bullet shells.
We proceeded further to the border, where we came across an eyry owl, that was remarkably tame. Was this some kind of sinister warning? After taking some film we stopped at the UN border barrier for some photos, before making our way out.
Željava Air Base Photos – Objekat 505
















On the way out we wanted to look at the abandoned aircraft near the base entrance. These turned out to be a DC-3 and two F-84 fighters, I was not able to work out the exact type. But they proved an interesting addition to the visit.
Zeljava History and Operational Summary
Zeljava Air Base, during its operational years (1968-1992), was a formidable military installation with impressive capabilities
Aircraft Capacity: The underground hangars could accommodate up to 58 fighter aircraft, primarily MiG-21s. This provided a significant air defence capability for Yugoslavia.
Command and Control: It served as a major command and control centre for the Yugoslav Air Force, coordinating air defence operations across the country.
Nuclear Bunker: The underground complex was designed to withstand a nuclear attack, protecting personnel and equipment in case of war.
Self-Sufficiency: The base had its own power generation, water supply, and other essential systems, allowing it to operate independently for extended periods.
Runway System: The surface-level runways could handle various types of aircraft, including fighter jets and transport planes.
Defense Systems: The base was equipped with radar installations and anti-aircraft defences to protect against enemy attacks.
Strategic Location: Situated near the border with NATO member Italy, it was strategically positioned to respond to potential threats from the West.
At the time Zeljava Air Base was a state-of-the-art facility, playing a crucial role in Yugoslavia’s defence strategy during the Cold War era.
Construction and Purpose:
- Cold War Era: Construction began in 1948 and was completed in 1968 during the Cold War under the Socialist Federal Republic of Yugoslavia (SFRY).
- Strategic Importance: It was designed as a major military air base and nuclear bunker, intended to withstand a nuclear attack and serve as a key facility for Yugoslavia’s air defence system.
- Underground Complex: The base featured an extensive underground network of tunnels, including hangars, command centres, barracks, and other facilities.
- Expensive Project: It was one of the largest and most expensive military construction projects in Europe, costing billions of dollars.
Operational Years:
- Yugoslav Air Force: Zeljava Air Base was primarily used by the Yugoslav Air Force (JRV) from 1968 until its destruction in 1992.
- Aircraft: The base housed various aircraft, including MiG-21 fighters, which were a significant part of the Yugoslav Air Force’s fleet.
- Secrecy: The base was shrouded in secrecy during its operational years due to its strategic importance.
Destruction and Abandonment:
- Yugoslav Wars: In 1992, during the Yugoslav Wars, the Yugoslav People’s Army (JNA) destroyed the base to prevent it from falling into the hands of enemy forces.
- Explosives: The JNA detonated explosives within the underground tunnels, causing significant damage to the complex.
- Environmental Impact: The destruction also resulted in environmental contamination due to the release of fuel and other hazardous materials.
Current State:
- Abandoned: The base remains abandoned and in ruins, with the surrounding area heavily mined.
- Tourist Attraction: Despite the risks, Zeljava Air Base has become a popular destination for urban explorers and those interested in Cold War history.
- Preservation Efforts: There have been discussions about preserving the site as a historical monument, but no concrete plans have been implemented yet.
How to Get to Željava – Objekat 505
Željava Air Base Map
Getting to the Željava base is pretty easy, it is on Google Maps and will take you about 20 to 30 minutes from Plitvička National Park. Get directions here.
Željava Air Base Plan and Map

Zeljava Video
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References / More Information
I found most of the info I wanted by following links out of Wikipedia and Željava Lybi.

Dan’s a windsurfing, adventure-seeking nomad with a passion for exploring the globe overland and an Engineer. Having grown up in the Middle East, he brings a unique perspective to Getting Lost Again, sharing his love for discovering hidden gems and embracing the unexpected. When he’s not on the road, he finds inspiration in windsurfing and other creative pursuits – and is equally at home under a vehicle solving problems as he is exploring a new place.