It has to be somewhere in Croatia ... Could you tell me where?
The sign on the left could be a hint to an observation point or a hotel. Maybe it says „Plaza“ or something?
It says plaža, which means beach, got any other clues?
no, unfortunately not. Searched castle-like buildings in coast area up and down of croatia but can‘t see a tree on those platforms.
Register on a Croatian forum like index.hr and ask there. Since they're desperate for tourists they'll be more than glad to tell you.