Here's an interesting TEDx Vienna talk by Bradley Garrett about the role trespassing plays in a democratic society and in one's own creative self-expression. I find myself agreeing with what Bradley is saying here -- that preventing somebody from entering a premises is usually disguised as a means of security. But security from what? From terrorism and terrorists? From people potentially injuring themselves and finding the building owner liable? What sort of society are we living in where we as adults are not allowed to weigh the risks of exploration for ourselves but instead need to be told DO NOT ENTER?
Bradley then goes into how the notion of security in NO TRESPASSING signs is incredibly weak. Because in many cases, you can pay to explore places and take photos, which really wouldn't hinder anybody (like a terrorist) from doing the same and getting that information legally.
Often, I find myself just straight up walking into places I don't belong and opening doors that don't seem to be locked. I disregard the signs altogether most of the time because honestly, the consequences of being caught and told to leave isn't really all that big of a deal to me if the other side of the coin is being able to get a good view of something fantastic.