Okay, I've discovered something odd today. I was playing through Morrowind GOTY on steam... and I found an area I didn't find in any other play-through of the game. I've googled left and right and I can't find any info on the area. I'm not certain if they are added on in the mods I'm using. But I've completed those mods and never found this.
Maybe a spoiler.

I was in Dagoth Ur's dungeon. Even though I hadn't picked up Sunder yet I was looking for him anyway. I didn't have any luck finding him. I found lots of weird things though. What appeared to be the shoes of a construct with valves on the bottom that appeared to be very old and were stuck. Certain valves didn't turn. Keys were needed that I didn't have. And all around I was seeing these strange cylinders that did nothing but had "?" marks appear when I hovered over them with the cursor. There was also a room with a shrine, and in that room, a "Sphere of passage". I couldn't figure out how to get in. After reading on some forum about ash statues being batteries I took them all out of the monolithes of the shrine. The sphere opened and inside was one of those tubes, but it was open and had a button to use a teleporter. It took me to "Dagoth Ur, Hall of Passage" or something of that nature. I picked one of the many cylinders in the room: One labeled "portal" I found myself in a room flooding with water. I found a secret door, travelled up it, And found myself in a "Lost Dwemer Ruin". In the ruin were numerous dwarven constructs and goblins (I have tribunal installed, but I haven't done anything past kill the assassins that showed up. When I checked my World Map the cursor was over Solstheim. I could also not levitate in these areas, and there was a black piece of wall that said something along the lines of passage to Mournhold. I took it and it was a dead end, though clearly part of the cities sewers. Another room appeared to be a factory for making constructs, there were about 10 in the room, which was filled with green light. A long table in the room had many pieces of the constructs not yet put together.

Can anyone else confirm this? Has anyone ever seen it before? Have I stumbled upon hidden content in the game? The UESP wiki says nothing about any of this. It only mentions the direct route to Dagoth Ur. o.O

Nevermind. After finding a creature named Darknut I believe this is part of his Greater Dwemer Ruins mod. I didn't even know I had it.

This is the best kind of discovery, when you discover modded content without meaning to. Just as it should be.
Most install a mod and immediately locate the content.
Justified sometimes, personally I go straight for armor/clothing that's newly downloaded.

Well that's hilarious :laugh: