By the end of the 19th century, Fort Kluže, a now touristic fort right off the motorway, had fallen into disuse because of the rapid development of artillery. In order to have sufficient fortifications in the area the construction of, the upper fort, Fort Hermann, began in 1897.
Best access is to park your vehicle at Fort Kluže then hike up. Don't forget a headlamp!
About the source: Atlas Obscura
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