I have been working on this MASSIVE fortress for GM mode for over the past week. I call it Fort Hope. It has a check point for magisters to check people's identities across the bridge from the entrance, a garden, a magister's barracks, a chapel and, at the very top of the mountain it is built upon, a prison. Well, the building you see at the top is just the entrance to the prison. The prison itself is built deep inside of the mountain and holds my island's most dangerous sourcerers.
It is still a work in progress and looks absolutely gorgeous in game. The below screenshots from the editor do not do it justice at all, but nonetheless, feast your eyes upon what I have done so far.
GMAddon1: Adds almost every single monster and NPC from the main campaign into GM mode, plus a few large custom maps to use in GM mode.
Very impressive. I have done a ton of scene work in Mount and Blade: Warband for the Persistent world mod in the past (persistent multiplayer roleplaying mode). So large, realistic maps etc. I found it fairly easy to work with and made some decent stuff, though, I've been trying to learn mapping for Divinity but its pretty slow going. Nothing like what you are showing here.
I truly appreciate the effort you and others put in to helping the community. That includes the mod you are working on for expanding GM mode. Much appreciated and I can't wait to see what this game mode will be after a few more months time.