Weird gate near the gate of Thal in central thanalan?

[Phyllo]

That I know for the crossing, but at least the crossing have some Npc that explains it (I still don't understand how the hell we get from north shroud to coerthas trough a way that previously was a huge mountain wall and now some nice little road near the river xD)

Same for the road the used to lead to the west part of coerthas they also explained it but this one door...
Fun fact, there's a stone bridge that leads int he same direction the door leads to in southern thanalan (right under the forgotten springs)
We can't access it due to some magical invisible wall but the rope/fence that surrounds it clearly shows that it's a bridge..

Wait a sec.. Wasn't the underground road toward the sildih ruins supposed to be north of the nald gate?
I know the the ruin itself is located in sagolii but we can't access in ATM, we can only walk a tiny bit of the desert (there's also some obvious path that lead toward the rest of the desert but blocked by an huge boulder)
But would it be dangerous to have the gate to lock away sildih just by the town gates?

[Nialle]

That I know for the crossing, but at least the crossing have some Npc that explains it (I still don't understand how the hell we get from north shroud to coerthas trough a way that previously was a huge mountain wall and now some nice little road near the river xD)

That entire connecting area was blasted by Bahamut, though the damage is most obvious from the Shroud-side. So that's why it's passable now.