GM Challenge - What’s in the village?

[Misereor]

I have my own answers, which I will post later, but I want to see what other people will do with the set up.

First the apparently obvious.
- Who built the engineering masterpiece. Answer: Someone capable of building it (duh!).
- Why would someone place something in plan view if they wanted to hide it. Answer: They wouldn't.
- Why would someone hide the access to something that is in plain sight? Answer: Since someone is bound to notice eventually, either to generate interest or to get them used to the idea of a village being there.

The why of it.
To see who is capable of finding the access?
To divert attention from something else that is not ordinary?
To get them used to the village without actually meeting the inhabitants. Until it is time.

So I'm thinking a San Marino scenario.
The inhabitants are people who would ordinarily be persecuted, but led by a builder of extraordinary ability they found refuge in an inaccessible valley.
Since the bridge is of reasonably contemporary design but doesn't actually appear to be used by the village, the reason it was built was to make sure that people from the local area use it instead of the route where they would discover the actual access to the village. Of course the party does find the access (after a bit of carrot waving), but before the inhabitants are ready, and thus there is a decent chance that they will inadvertently set off a conflict. Possibly religious, possibly dynastical, possibly criminal, possibly local, possibly regional, or possibly with neighbouring powers.
Objective: Deal with it.

(Non-system or power level specific. This should work with most settings.)