ShotHotspot has mapped 15 abandoned places in Barban, Istria, ranked by how often they're photographed, viewed and voted for. The most popular are Haludovo Palace Hotel, Old Abandoned House and Bunker. Some are private property or unsafe, so get permission before you visit.
We don't know whether you're allowed to visit any of these places. Many are private property, closed to the public or unsafe: get permission from the owner or the relevant authority, and take safety precautions.