The Crossroads will smell mostly like the various things in it—metallic statues, stone/rubble, water, etc. But it’s also being held together by magic, so it will also have the sort of ozone-y smell of active magic.

Going through the eluvians is part of everyone's job here, since they need to note down where they lead! So no one is being a dumbass if they peek through them. It's just not the focus of the event, compared to the Crossroads stuff. Going through will lead to a mix of nondescript ruins in forests, deserts, caves, etc., as well as a few libraries or estates, some darkened storage rooms, and at least one storage crate that causes people to immediately hit their head on wood if they try to walk through.