Large Obsidian tower from the bottom of the map to the top, massive moat, like four or so of the minimap tiles around it, all the way to the bottom of the map, every wall on the outside of the moat bronze. The moat wouldn't be filled, it would be empty 99% of the time.
Lava would feed into the moat via a mass relay of "Triggers" which would be essentially prison cells that filled with lava, killing the occupants and setting off plates that unleashed the tide unto the pit, which burned away huge amounts of the dead matter that was down there.
I had hundreds of bodies at one point, some of them goblins that were still crawling with broken legs from the fall, others were humans (I play human civs.) that had fallen and since I never use health care professionals were left in the pit.
This causes some problems from an ethical stand point, I mean, I had a few custom creatures that were basically toned down dragons. Unleash them into the pit and basically anything left alive was munched on.
The interior of the fortress was rather lackluster, I had alot of one tile wide walkways that went between some of the latched on towers that hung precariously or were perched onto small outcrops.
Throne room was about 30 tiles from front to back, 15 tiles wide. It was also the entrance hall with a nice little pool and a view of the other side of the fortress. Workshops were in the SUB basement, a little above the SUB-SUB basement which had an arena and other various beasties that I could either unleash into the "pit" or let loose into the no man's land.
Of course eventually this place got overrun whenever I collapsed my entrance bridge with probably three dozen goblins and my soldiers, alot of the goblins lived through the fall and managed to clamour into this place while there was a show going on. I could have stopped the arena match, but the show must go on, even in war.
Individual bedrooms were no more, barracks woot! No real beauty besides the bloody brass statues that lined the battlements and walkways.
I gotta remake my Brass Blood Castle.