Lasthold: Possible Boss Fight Location?

[Catapult]

I've recently taken to reading the map text. The ruins are called "Gelmorra Ruins", making it one of few above-ground structures from the Gelmorra civilization.

...my lore-sense is tingling

That REEKS of likely being a location in the climax of the seventh umbral era storyline. What you're getting at is quite plausible. The Gelmorra ruins may hold the key to countering/dealing with Meteor.

Go check out Letter from the producer XXX for 1.23 dev-cycle updates.
"Addition and adjustment of Seventh Umbral Era-related monsters. Addition of Seventh Umbral Era-related objects."