Hmm...
Well there is an interesting route you can take, where it is known to people, but they just can't reach it for whatever reason. Humans are awfully good at taking weird things and filing the away as unimportant. Certainly some people would be interested, but I can't imagine the average Joe would bother after a while. It's sorta like how there are plenty of mysterious ruins on actual earth, and archeologists certainly care, but most locals have definitely already filed it away as "that thing that's always just been there is still there." Even if they have a myth associated with it, it's not likely to override their normal day to day concerns.
So maybe there's like, an impassable valley around it with high winds. Sorta like a moat going on. Just enough where it's really not worth the trouble for long enough that the protagonists can show up and get it done.