Zadar’s hidden tunnels and bunkers: 250 forgotten sites beneath the city

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Beneath the residential neighbourhoods of Zadar, around 20 metres below ground, lies a largely forgotten network of military tunnels and bunkers, a powerful reminder of the city’s turbulent 20th-century history.

Constructed from the late 1920s onwards, these underground structures were first built during Italian rule and later used in the Second World War and Croatia’s Homeland War.

Today, many remain neglected, flooded or partially buried, yet a growing group of enthusiasts and experts are working to document and preserve what survives.

Most of the bunkers were constructed in the late 1920s and 1930s, with additional fortifications added during the 1940s. At the time, Italy sought to strengthen its borders following the Treaty of Rapallo, believing it could consolidate its territorial gains along the eastern Adriatic.

Military history researcher Jurica Vučetić has been among the first to systematically search for and catalogue the sites.

“Google Earth helped enormously,” he explained to HRT. “From the air you can often see the domes. Little by little, all 250 sites were located.”

According to researchers, around 250 bunkers and tunnel structures have now been identified across the wider Zadar area.

For some residents, the tunnels are more than relics – they are part of childhood memory.

Zoran Krizman from the Bokanjac district recalls playing inside the tunnels as a boy.

“We were in there all the time. We didn’t have torches, so we lit bicycle tyres to see inside. We almost suffocated,” he said, describing a time when safety was secondary to curiosity.

Zadar

Accessing some of the tunnels today remains difficult. In one case, an entrance located within a private house was found completely flooded after heavy rain. Many of the deeper tunnels, some reaching 20 metres underground, are damp, unstable and pitch black.

HRT journalist Ante Kolanović described the experience of entering them as “like something from a horror film, truly uncomfortable and unsettling”.

Use During the Homeland War

The underground network was not merely a relic of the distant past. During the 1991–95 Homeland War, locals once again sought refuge inside the bunkers.

“When the bombing of Zadar began and the sirens sounded, we ran to the bunker,” recalled Mario Mrkić, also from Bokanjac.

Beds were installed inside some shelters so Croatian soldiers guarding the front line could rest. At the time, those who used them say conditions were solid and functional.

“They were built well,” one witness noted. “They served their purpose.”

Art historian and scientist Antonija Mlikota has been closely involved in research into Zadar’s tunnels and bunkers. She points to countries such as Switzerland, which maintains around 370,000 bunkers still designed for civilian protection in times of danger.

“Swiss bunkers are actively maintained and intended for civil defence,” she explained. “Ours cannot serve that purpose.”

Mlikota was part of an Interreg revitalisation project aimed at preserving and potentially repurposing some of Zadar’s underground heritage. However, the initiative has yet to be fully realised.

Today, much of Zadar’s subterranean military network remains out of sight and out of mind, concealed beneath homes, gardens and neighbourhood streets.

Yet as researchers continue to map and document the sites, there is hope that this hidden layer of history may eventually be brought back into public awareness.

For now, the tunnels remain in darkness, silent witnesses to decades of conflict, survival and resilience in one of Croatia’s most historic coastal cities.