Objekt Buna
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A former Yugoslav Air Force underground base/hangar inside a mountain near Mostar, Bosnia and Herzegovina. Completely abandoned since the wars of the 1990s and largely empty and also totally uncommodified for visitors, it’s still an exciting bit of “urbexing” when in the area. Good torches are a must for this!
More background info: It’s not easy to find much information about this underground airbase code-named ‘Objekt Buna’ (after a nearby river), far less so than for the similar but better-known and larger Željava system in Croatia.
All I have been able to unearth is that the tunnel was constructed between 1969 and 1971 as a top-secret operation. Apparently the decision for such underground bases was taken in the light of Israel’s success in largely destroying its enemy’s aircraft on the ground during the Six Day War of 1967. In view of how long it took to construct Željava (and how expensive that was), the new airbase’s design at Mostar was made simpler and easier to set up (and less expensive).
The ‘Objekt Buna’ tunnel is curved and ca. 300m (985 feet) long, some 14m (46 feet) wide and about 7m (23 feet) high. At the entrances at both ends of the tunnel there are massive concrete arches for protection, painted in military camouflage colours. An emergency exit was located at the top of the mountain above the tunnel.
The entrances used to have huge steel doors (20cm,/8 inches thick) with which the whole complex could be hermetically sealed, with air ventilation/purifying technology, supplies of food and water, a kitchen and dorms for all the staff inside the tunnel-bunker. There were also workshop areas branching off the main tunnel where aircraft repairs could be undertaken autonomously. There was space for a total of 20 MiG-21 fighter jets inside the tunnel. An access road led from the tunnel entrance to the neighbouring airport of Mostar (then a shared military and civilian airport, now only civilian). The aircraft did not use their jet engines to get to the airport but were towed there by tractors.
With the beginning of the Bosnian war in 1992, the airbase was given up and subsequently almost completely gutted. For many years the site was used as a rubbish tip so that the entrances were hardly accessible. But in recent years the site was mostly cleared, also inside, save for the storage of a few pallets and some debris at the northern entrance. The southern one is almost completely clear.
It’s not a tourist destination, though, and my driver-guide (of Funky Tours, Sarajevo – see under Bosnia and Herzegovina) did not know about it (though he was familiar with Željava). But intrepid travellers do go there with some regularity as photos posted online testify.
What there is to see: First you have find the place (see below) and if you’re travelling by car, you need to park by the gate that blocks the access road to the southern entrance of the underground airbase. The gate only blocks the road, but on foot or even with a bicycle or scooter you can easily bypass it. I also didn’t spot any “no trespassing” signs or anything. So you can just walk in.
At first there’s no indication what’s to come, but then as the road slightly bends right you come to the massive concrete arch over the tunnel entrance, still painted in military camouflage colours/patterns. When I visited, in April 2025, there was very little rubbish here – quite unlike what I had seen in older photos online. My contact at Funky Tours in Sarajevo also told me that when she visited the place some years ago, the tunnel entrance wasn’t even accessible for the mounds of rubbish blocking it. So there must have been a clean-up operation in more recent years.
Going into the bare tunnel you won’t get far without a good torch, because as soon as you leave the entrance opening behind and the tunnel starts curving to the right you are engulfed in total pitch-black darkness. I came prepared with a high-lumen torch which allowed for navigating through the tunnel safely, but even though, its light was not strong enough to light up any more than small portions of the tunnel walls and ceiling. The place just swallows light!
Still I was able to get a few photos (see below) and explore the full length of the tunnel. En route I passed two side tunnel areas, presumably the former aircraft repair bays. Eventually I came to a place that looked like bathroom facilities – totally gutted but the walls are still covered in white tiles. In the guttering in front of the facilities and along the side of the tunnel, I noticed a rat scuttling along. No surprise, really. This has to be perfect rat habitat ;-) And I can also imagine there being some interesting insect life in there. The pigeons, though, stay close to the entrances even though they too use the tunnel.
Here and there you can make out objects dangling from the curved tunnel ceiling. I assume that these must be remnants of former light fixtures.
At one stretch of tunnel, I encountered stacks of wooden pallets and some packages, so obviously someone still uses part of the tunnel for storage. There were also some broken glass bottles and other bits and pieces lying about, but overall it was comparatively clear of debris – except at the northern tunnel entrance where there was noticeably more rubbish, including car parts and piles of old cables or hoses.
I did not use the northern entrance for exiting the tunnel, though, but instead retraced my steps to get back to the southern entrance and its access road, at the end of which my driver-guide had parked our car.
Across the main road, also take note of the gate to the airport access track, which the planes from the underground airbase would have used to get to the runway. This gate is locked and “adorned” with “no entry” signs (unsurprisingly, as there’s an operational airport beyond).
I found this little excursion and exercise in urbexing en route into Mostar a most exciting add-on to the tour I was on. Fortunately my driver-guide was flexible enough to allow for this extra stopover (though he didn’t venture into the tunnel with me himself but just waited by the car ). I had been following the route we were going on Google Maps so knew we were near, but it then popped up rather suddenly. So I shouted out “it’s right here” as we came to the gate/access road and he pulled in. He then confirmed with some local hikers/dog walkers that we had indeed come to the right place. I’m glad it worked out that way.
Mind you, though, this is not a tourist site, and there is absolutely no commodification of any sort. It’s just raw.
Location: just south of the district/village of Gnojnice, east of the northern end of the runway of Mostar airport, some 3.5 miles (6 km) south of the city centre/Old Town.
Google Maps locators:
Gate at the access road to the southern entrance: [43.2922, 17.8463]
Southern entrance: [43.2935, 17.8473]
Northern entrance: [43.2958, 17.8467]
Access and costs: quite hidden, but if you know where you’re going, not so hard to find; freely accessible.
Details: To prepare for a visit you should use the GPS locators above to have a “test run” on Google Maps so you know where to go. I strongly recommend using the southern tunnel entrance, as it’s cleaner and it’s easy to park by the access road gate.
If you have your own (rental) vehicle or at least a bicycle, you can make your own way to the site, which is just off the main road that goes past the airport of Mostar to the east (whereas the airport terminal building is on the other, western side). But it’s really a bit out of walking distance from the city centre of Mostar.
When I visited the site, it was as an add-on I specifically requested from my driver-guide, with whom I was on a four-day, private round trip by car through eastern and southern Bosnia with Mostar as our base, plus Banja Luka and its environs at the end. The trip was organized through the operator Funky Tours who are based in Sarajevo (see their sponsored page here). ‘Object Buna’ was not nominally part of our itinerary, but my contact at Funky Tours had said we’d be going close by so that I could request an extra stop, and so I did. My driver was at first a little confused, as he was unfamiliar with the site, but we worked it out. I knew from my online preparatory research where I had to go, so he just took me there and left me and my wife to explore the tunnel while he waited by the car.
If you want to go inside the tunnel a really good torch/flashlight is indispensable. You simply cannot do it without. I had a pretty good high-lumen torch, but even that was not able to light the tunnel up save for short distances. For better photography than I managed (see below) it might be a good idea to come armed with stronger lights, not just a torch.
Also: wear sensible shoes and clothing. There’s broken glass and some debris on the ground and it’s a dirty environment (and you might encounter rats). Note, too, that if you enter the tunnel you do so entirely at your own risk, so you really have to take care. There will be no mobile phone reception inside the tunnel either, so better not break a leg while in there ...
Time required: I spent about half an hour at this site and inside the tunnel. I could have explored for longer, but I didn’t want to leave my driver-guide waiting too long, given that this was a specially requested off-itinerary stopover.
Combinations with other dark destinations: It could have been interesting to also go up the mountain to find the emergency exit and ventilation shaft above the tunnel. But with my driver-guide waiting by the car, I didn’t think I could afford the time for that.
Other than that see under Mostar and also Bosnia and Herzegovina in general.
Combinations with non-dark destinations: see under Mostar and also Bosnia and Herzegovina in general.
The tunnel’s location is not touristy, but the surrounding area is used by locals for hiking and walking their dogs. There are hiking paths in the forested land above the tunnel.
A bit to the south of the tunnel, and nominally still part of Gnojnice, are the “Emporia” vineyards, which not only offer wine tastings but also overnight accommodation, a restaurant and a pool. I didn’t stay or eat there but can vouch for the quality of their wines, especially their Žilavka (white).
