Secret Spot: Underground Tunnels in Croatia

Pula Zerostrasse

Picture the perfect honeymoon: sunny beaches, world-class wine, and… underground tunnels? Fortunately, my new husband did not mind a detour through a former bomb shelter on our day trip to Pula in Croatia. A few days later in Zagreb, we heard about another underground passage. How could we I resist? Two Croatian underground tunnels hold subterranean stories ranging from wartime shelters to hosting raves.

Now Entering the Zerostrasse

Pula is an ancient city on the Adriatic coast that boasts many Roman relics, including a Roman mosaic hidden in a parking lot. Somewhere between hunting down that mosaic and touring the Roman amphitheater, I heard about a network of tunnels under the city.

Pula's Zerostrasse

Pula’s built underground tunnels, called the Zerostrasse, during WWI. Pula was an important naval site for the Austro-Hungarian Monarchy, so the tunnels were part of a fortification system created to protect the city, civilians, soldiers, and ammunition.

Tunnel underneath Pula, Croatia

The tunnel system stretched across the city underneath Pula’s hills. Consisting of passages, trenches, galleries, and communication passageways, it provided shelter from air raids. The two of the largest tunnels were built under the Kaštel and Monte Ghiro hills. Underneath the Kaštel, tunnels with entrances from four different sides connect in a central space.

Map of Pula's Zerostrasse
Credit: Historical and Maritime Museum of Istria

It’s fascinating to walk the tunnels today and picture how the storage areas were once used. While damp and a little wet, the cool tunnels offer a break from the Adriatic sun. Their design offers regular air flow and a temperature around 60 degrees Fahrenheit. Varying from 10 to 20 feet wide and about eight feet tall, the tunnels are more spacious than one might imagine.

Pula's underground tunnel

Over the years, the tunnels expanded under Italian rule and designated as fallout shelters and emergency hospitals after WWII. Today, Pula’s shelters and tunnels can hold more than 50,000 people, nearly the entire population.

The tunnels also include exhibits by the Historical and Maritime Museum of Istria. On my visit, the exhibit covered the history of public transit in Pula. What an unexpected find and one of the most unique museum settings I’ve experienced! Whether you’re there to learn or you want a shortcut across town, Pula’s Zerostrasse offers a side of the city that you shouldn’t miss.

Museum in Pula's underground tunnel

Underground Zagreb

A few days later and 120 miles away, we enjoyed a stroll on the Strossmayer Promenade in Zagreb’s picturesque Upper Town. We stumbled on the tunnel entrance beckoning in a wall near a park and back underground we went.

Zagreb tunnel entrance

The network of tunnels hidden underneath Zagreb’s Gornji Grad or “Upper Town” are shrouded in mystery and urban legends. Grič Tunnel is the only part of this network that is open to the public. Zagreb built it in 1943 to shelter civilians from air raids.

Grič Tunnel Zagreb

The tunnels fell into disrepair after the war. Legends include tunnels that end below the Croatian Parliament, a bunker in the Sljeme mountain, and use by the Yugoslavian Secret Service. During the Croatian War of Independence, the tunnels became bomb shelters once again. Grič Tunnel also became the site of rave parties as a resistance to the war. In 1993, MTV covered the Under City Rave. As an attendee named Robert said, “We want music, we want peace, and the whole world knows that.”

entrance sign in Grič Tunnel
“Entrance” sign in Grič Tunnel

Grič Tunnel was renovated in 2016 and is now accessible from five different points. The tunnel entrances are marked with the Zagreb coat of arms. It sometimes hosts cultural events like Advent celebrations and historic exhibitions. Grič Tunnel is a quick shortcut through Croatia’s capital city and the site of some handy public toilets. Walking through the 350-meter-long tunnel, you can still see old warning signs posted and imagine electronic music echoing off the walls.

exploring croatia's Grič Tunnel underground
sign in Zagreb's secret tunnel

While the underground tunnels in Pula and Zagreb were built as a necessity in the dark days of war, they welcome visitors today with a museum encounter like no other and a unique way to experience these cities.

Gric Tunnel entrance in Zagreb, Croatia

Zerostrasse
Carrarina ul. 3, 52100
Pula, Croatia
Admission: 15 HRK (Adults)
Hours: 10 a.m. – 8 p.m.

Grič Tunnel
Mesnička ul. 19, 10000
Zagreb, Croatia
Admission: Free
Hours: 9 a.m. – 9 p.m.

Sources

Jessica Mlinaric founded Urban Explorer in 2010 to inspire curious travelers by highlighting history, culture, and hidden gems in Chicago and beyond. She is the author of 'Secret Chicago' and 'Chicago Scavenger.' Jessica has visited 20+ countries and 30+ U.S. states. She has more than 16 years of experience as a marketing strategist and works as a freelance writer and photographer.