I'm in the final chapter of the game, and I've reached the second level of the ravaged capital (the "central passage"). In the southwest corner of this map, there's an area with a couple of loot caches on it which I can't figure out how to get to (see attached image). It looks like you ought to be able to just walk across to it, but when I try, I bump up against an invisible edge. I can't find any area transitions that would let me climb down to it either. Does anyone know how to access this spot?

Dimension door :)