Zeljava Airbase

Željava Airbase, military code Objekat 505, is a Cold War underground airbase carved into the base of Plješevica mountain, right on the border between Croatia (Lika) and Bosnia-Herzegovina (Bihać municipality). Started in 1957 and brought into service in 1968, it was built to shelter Yugoslav MiG-21 squadrons, their crews and their support infrastructure under hundreds of metres of solid rock, with three runway heads pulled inside on the approach of an attack. At the time it was reportedly the largest underground airbase in Europe, and one of the most expensive military projects Yugoslavia ever undertook — estimates still hover around six billion US dollars in current terms.

What was inside

The complex had roughly 3.5 kilometres of interconnected tunnels, with hangars, command posts, fuel tanks, water and power supplies, crew quarters and decontamination chambers, all designed to survive a direct nuclear hit on the mountain above. The aircraft were pushed in and out on tow, into the four tunnel mouths cut into the hillside. The runways themselves were outside, four long concrete strips running across the karst, two on the Croatian side and two on the Bosnian side, all sharing the same flat approach corridor.

The end of the base

The base was used by the Yugoslav People’s Army (JNA) until the 1991 to 1995 war. In late 1991, with Croatian forces advancing on the area around Bihać, the retreating JNA destroyed the runway heads, the tunnels and much of the interior, partly to deny the facility to any of the warring sides and partly because the federal army was no longer able to hold the position. The destruction was extensive. The base has been abandoned ever since.

Why it is dangerous

This is one of the most dangerous abandoned sites in the region, and the warnings are not bureaucracy:

• Unexploded ordnance. The area around the base was heavily mined during and after the war. Some mines have been cleared from the immediate runway approaches, but the surrounding woods are not safe to wander into.
• Toxic air in the tunnels. The interior was flooded and sealed for years. The air inside is bad, low in oxygen and contaminated with fuel residue and asbestos from the original construction.
• Unstable concrete and roof falls. The 1992 demolition damaged the tunnel linings, and sections of the roof have come down since.
• Border sensitivity. The runway crosses an international border. The Croatian and Bosnian sides are both signposted.

Do not enter the tunnels. Walk the runway, photograph the entrances from outside, and treat the warning signs as fact, not decoration.

Practical info

• Entry: there is no official entry, ticket booth or information point. Visiting is at your own risk. Most visitors park near the Croatian side at Izačić and walk to the runway.
• How to get there: about 30 minutes from Bihać (Bosnia) and roughly an hour from Plitvice Lakes (Croatia) on the Una river road. The last stretch is gravel. A 4x4 is helpful but not required in dry weather.
• Time needed: an hour or two on site is plenty to walk the runway heads and see the tunnel mouths. Do not budget time to go inside.
• Combine with: the Una river, Martin Brod and the Strbački Buk waterfall are all close on the Bosnian side and make the long drive worth it even without the airbase.

For photographers

The big shots here are about scale. The four runway heads, with the tunnel mouths gaping in the hillside behind them, are the iconic frames. The cracked concrete with weeds pushing through reads as a textbook Cold War ruin. The light is best early or late, when the long shadows emphasise the runway lines. A drone (where legally permitted) is the only way to show how the four runways line up with the tunnel mouths. Stay on the concrete; do not be tempted closer to the entrances.

Every spot here is mapped and verified by Photograph by John. Share this guide if it helped plan your trip.