Originally Posted by cthulhu
I seem to remember seeing the blue square on/in/around The Dark Portal in Blasted Lands. On the other hand, I might be wrong, but it could be worth a shot.
It might be a bit hard getting there with a low level toon, though. ;-)
It's hard to spot though as it basically makes the whole portal brighter. jiggling the camera and/or moving temporarily fixes it, but not long enough to take a "working" screenshot. You would need to be about lvl 55 to reach it. with some ease.
I tried to find the deadmines portal as that's low level, but couldn't find it.