Well, while thinking of dungeons (modding) & with how people are against any hostile entities I thought this type of feature might work as a middle ground. Basically finding landmarks, points of interests, and such which you can voluntarily capture by putting a flag icon on it to attract NPC attention. The things like dungeon entities & bandits, and whatever else we're getting. You don't have to go to these, yet if you did, you'd have to make sure to keep it safe from any hostiles coming your way. Once the settlement is activated it would stay activated for as long as it stays there. It can either be fully destroyed, or even recaptured by the locals, enemies, or whomever stumbles across it.
I guess I'm thinking of Pokemon GO gym type things, or even those used in PVP MMO games. ANybody played 'King of the Hill' mode in Perfect Dark, or similar games? Yeah, something like that. It's your choice if you wanted to do something like this, for those even wanting to shy away from hostile entities, that they could be kept to dungeons & even be rotational, active, and as an in game event.
- What to control? Relics, structures, or even vehicles similar to structures. Even ancient, or old/futuristic buildings. Not really radar, just abandoned buildings, bunkers, and such. [Use Terraria & Starbound as inspiration, if needed.]
- How to activate your control over it? Upon discovery, one would either have to place a flag in a flag pole, interact with a command pad, or something appropriate to the structure.
- NPC Curiousity: Once the 'key' is in place you would then alert people's interest through curiousity. Not right away, yet over time that if in Medieval era you'd see flames in the distance gradually coming near as days pass. Maybe even some auditory cue of some sort of popping, snapping, or just chatter in the distance. If you're miles away then none of these would happen, yet if nearby you'd defiantly notice humanoid NPC activity. Modern wise, if we have radio, you should be able ot hear specific stattic type noises, or even creepy radio chatter of people roaming closer. Even being given text notifications if you have a digital device with communication on it.
- AI Takeover: IN a similar manner as you taking over the 'landmarks', the AI would be able to do the same, if clever enough. Even a Medieval entity could take over a modern structure, if in a longer time process when left unchecked. If you didn't put up walls, didn't defend it yourself, nor use NPC comrades (if we ever do; NPC Traders, or whichever) then the AI could have a 80% chance of taking it back from you, maybe even claiming everything you put there as their own. Any vehicles & such in the area being theirs, yet you can still steal it back from them, yet with a bit of frustrations with lock changes & such 
I'm trying to keep the thought simple of a 'king of the hill' type 'dungeon' implementation for people want to attract attention, or to simply defend. Not every checkpoint should attract attention, yet most of them should. I'm basically thinking Empyrion with the drone feature of you needing to go over to the Point of interest to destroy the antenna. This is taking it a bit further that, and in reverse, that you would attract curious NPCs to come check things out, if in a necessary delayed manner. A few in game days, weeks, or whichever. They will come.
If this works in vanilla, that be sweet. If it's modded, that's also neat. Whoever does it first & the best gains my respect. 
