Spoiler for the Mistlands boss if you don't want to know anything about the general area:
I'm assuming many people already know about this, but haven't seen a post on it – so sharing that there is so much more to the location of the Queen than just a staircase leading up to the portal. A small wooden wall can be removed along the side of the staircase revealing a furnished interior. What's more, the marble along the back wall can be removed to reveal quite a bit more space (some of it needs to be excavated) – a few ballistae on the top wall to defend against Gjalls and at least in this world, anything else is going to have a very, very hard time getting to me (on the pinnacle of a rock). Set up a stonecutter even before defeating the Queen and repaired all the stonework.
Hope crafting the Dverger woodwork (and doors!) is coming soon!
Source: https://www.reddit.com/r/valheim/comments/zucjfu/mistlands_boss_base_location_spoiler/