ShotHotspot has mapped 12 abandoned places in Donja Voća, Varazdin, ranked by how often they're photographed, viewed and voted for. The most popular are Slovenske Konjice Castle Ruins, Ruins Castle Kalnik and Ruins Tam Public Bath. 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.