Purely by chance — I was doing a Google Images search for some Ultima-related artwork, but not specifically Ultima Forever-related — I happened across the above image at the portfolio website of digital artist John Cipriani, who at least for a time was in the employ of Mythic. (His site suggests that he worked on both Ultima Forever and Dungeon Keeper.)

Much of the art in his U4E portfolio is stuff we had already seen — portraits and areas that had been featured in other screenshots. However, this one image stood out; it’s not something that I can recall seeing elsewhere.

I suspect that this was meant to be the topmost room of Blackthorn’s Castle, which can be seen in this screenshot from the Ultima Forever alpha test:

It’s the polygonal rose that gives it away; the same rose can be seen in the artwork for the castle’s foyer.

One wonders what arcane experiments Blackthorn — or one of his subordinates — might have been performing in this dark and mysterious chamber. Would that we had been given the chance to find out!