Inside Abandoned Underground WWII Fortress Built by Mussolini

An urban explorer has wowed the internet after sharing footage of the interior of the abandoned World War II Italian mountain fortress Monte Lesco.

The huge underground bunker and tunnel system runs along the former Italian border in Croatia. It was constructed under the instruction of fascist dictator Benito Mussolini during the interbellum as part of the eastern Alpine Wall or Vallo Alpino.

The Italian system of fortifications spread over 1,000 miles across Italy's northern frontier and the defensive line faced France, Switzerland, Austria and Yugoslavia.

The YouTuber who shared the incredible images and footage goes by the name Roach. An urban explorer, he often shares his adventures and explorations online.

"I spent about two hours inside, but I explore many of these types of bunkers and document them," Roach told Newsweek.

On Reddit, the explorer shared a nail-biting image of a steep spiral staircase that left viewers' jaws dropping.

"I actually went up the steps and back down as there is only one entrance to the fort," he said: "There are several large hallways and barracks. This particular one was partially destroyed by retreating Germans in WWII when they detonated explosives."

In a video shared on YouTube under his handle TattooedTraveler, Roach took his viewers along as he entered the Monte Lesco fortress and took a look around.

"That staircase is definitely something, scary too," said one commenter: "Must have been something to see how it was constructed. I don't think I would be able to explore places like that and no way would I have survived being stationed there."

An Airborne Infantry Veteran himself, Roach is fascinated by military history.

"I started exploring these places on my own and just taking short videos and photos," he said: "Once I realized almost no one had published content about them I decided to move to YouTube."

With many disused and destroyed buildings across Italy and Croatia, including schools, barracks and military fortifications, a friend of Roach is currently leading a project called REVIVAL to restore these areas.

While urban exploring can be dangerous, the REVIVAL project aims to make these historical areas of interest safe and accessible to the public for education and tourism purposes.

Until then, Roach hopes to share more incredible spaces online: "I truly enjoy learning and sharing the history of these places because the country doesn't really advertise them and you have to do research—a lot through authors and friends, because you can't find much online," he said: "It's almost like solving a bit of a mystery."