These are the dark remains of Yugoslavia's biggest military base. During the Cold War, the isolated Socialist state wanted to demonstrate its military strength with this partly-underground airfield. It was built in a no man's land that's today's border strip between Croatia and Bosnia-Herzegovina. By now, this has become a huge, almost forgotten area that still holds invisible threats.
In the endless tunnels, there was room for 80 MiG-21 fighter jets and more than 1,000 soldiers. This is the Yugoslavian version of "Top Gun", code-named "Object 505". There’s no fence, no gate, or even a sign indicating we were entering a former military area. But an old plane dumped decades ago indicated we have arrived. This is a Douglas C-47 - initially, a US-built military transport aircraft from World War Two.
The tunnels extend over several kilometers. The site was developed between the 50s and 60s. In these two decades, an incredible six billion US dollars were spent on the construction, making it the most expensive building project in Yugoslavia. Due to inflation, today's equivalent of the costs would be much, much more.
The tunnels were built wide enough for two MiGs standing side by side. The need for the facility arose in the 50s. Yugoslavia felt threatened by the two great powers to the West and East. A remote but strategically important area was sought to build this military base. This location was perfect since it was close enough to the border, so that potential attackers and ballistic missiles could be detected in time. Meanwhile, the combat aircraft could take off undetected, as the runways were in a radar shadow behind the mountain. The underground complex was also designed to sustain a direct hit from a smaller nuclear bomb. For that, the four entrances were protected by 100-ton pressurized doors. With an underground water source, power generators, and crew quarters, the military facility was largely self-sufficient. Stocks for food, fuel, and arms could last up to 30 days.
During the Cold War, this supersized facility was never in real use, except for exercises and reconnaissance missions. That changed in the 90s when Yugoslavia declared war on itself. When the constituent republics of the multi-ethnic state voted for sovereignty, the army tried to suppress these independence efforts. Some of the warplanes that terrorized Slovenia during the Ten-Day War in 1991 took off from here. Later, attacks on Croatia were also flown from this airfield. As a result, Croatian pilots began to desert. As the surrounding area turned into the frontline, the Yugoslav People's Army decided to withdraw. On the morning of May 16, 1992, air force commanders issued orders to abandon and destroy the Željava Airbase.
