That place where the Ascians gathered....their wording makes me think it's not Ishgard, due to how they referred to the Northlands as though they weren't there yet. I wonder if it could be under Ul'dah? It does resemble the gaol that Raubahn was in.
Also....why didn't Nidhogg show up at the siege? I thought it was rather strange at the time, like he might be related somehow to the unfolding plot with the Crystal Braves. Then again, I was disappointed no Dark Knights, Astrologians, or Machinists were showcased at the Steps of Faith.