Mild spoilers follow
Thanks to a recent BioWare news piece First Look: Halamshiral we now know that the Inquisitor will get to attend a masked ball at the Winter Palace in Halamshiral. It's not just any ball though, the Winter Palace has been selected as the site for peace talks between the two opposing sides of the Orlesian Civil War and the Inquisition goes there to stop an assassin. But level designer Chris Corfe notes that when visiting the palace "Combat is not the main focus... Intrigue and social interactions rule the day".
In this article Corfe and senior environment artist Ryan Love also talks of some of the inspiration for the palace. As one would expect, ornate palaces such as Versailles and Buckingham Palace were mentioned, but perhaps somewhat surprisingly, they cite Middle Eastern design a source of inspiration too.