I came up with this theory a while back, and after seeing Blackreach well...
Vvardenfell was supposed to be the capital city of the dwemer, it even means 'City of the Shield' but it appeared to be nothing more than just an island with a few small ruins dotted here and there.
But digging deeper, it seems that many of those ruins have closed off or caved in areas that we can't reach.
Now compare this to Blackreach, it's a huge underground city that is connected to most of the other ruins in Skyrim.
Could it be possible than way underneath Vvardenfell there's the actual city of... well Vvardenfell, and the other ruins are just surface access points to it?

Well the Dwemer lived on Vvardenfell before the Velothi (I think), so a larger underground city network isn't out of the question.

With the prevalence for magma in Dwemer ruins and with Vvardenfell being a volcanic island, I'd say it's unlikely. From what we saw in Morrowind, I'd speculate that Vvardenfell must have a huge magma chamber under it, and numerous areas where magma is close to the surface. Unless the dwemer are masters of bauxite, I doubt they'd have very much constructed beyond the "magma table" in any particular area.

Now, they might have something like that close to the surface of Red Mountain's cone, but it wouldn't be the kind of massive, open-spaced structure that Blackreach is. More like tunnels circling the lava chamber within the stratovolcano.

I wouldn't discount the ingenuity of the Dwemer. They strike me as masters of metallurgy, so taming magma might not be such an impossible task for them. Also I'd expect the Dwemer to make marvelous use of the magma as a source of geothermal power.

In fact, I remember seen magma pits in Dwemer ruins. I think they were in enclosed pools too, which would prove that they did in fact develop an incredibly heat-resistant alloy.

Using magma to your benefit is one thing, trying to build the equivalent of an Under-magma base is another. They might have had bauxite pumps, but pumping magma into your fortress is a lot easier than building through significant amounts of magma.

I remember the entirety of Vvardenfell being one giant, networked web-like Dwemer settlement. A singular city rather than a dozen smaller ruins. I don't know where I'm getting that from, though - might just have been fan fancy.

I'm going to agree with DarthRaveger: Vvardenfell's volcanic dust-soil and unstable tectonics weren't really suited for large underground construction. Skyrim's rock, on the other hand, was, and building down made sense from an insulation standpoint.

There were probably at least connecting tunnels (if not wholly connected systems) linking all of the ruins on Red Mountain together, for virtue that they describe the Dwemer's capital as a fortress and not fortresses.


My devil's advocate instincts immediately say "and you're going to tell me that the Dwemer just found a huge cavernous chamber sitting in the heart of Red Mountain from which they set about constructing a giant robot?" But I happen to agree with you about that. Given the architectural differences between geography and the story of Rourken, it might appear that there was at some point several nations of Dwemer, but they all seem united at least in their method of exit from reality. This idea suggests that Red Mountain (and possibly Bamz Amschend) were capitals over a Morrowind clan, Blackreach in Skyrim, and maybe Fang Lair in Hammerfell.

I have to say no on the giant underground city thing. I believe there is mention somewhere of individual Dwemer clans or workshops living within each small ruin. It was mentioned in dialogue on Vvardenfell. There were larger cities as well, like Bamz-Amschend (although that's on the mainland) and certainly it's reasonable to assume many Dwemer ruins have been lost to time, they weren't all connected and remained independent settlements for the most part.

What if this underground system did not just apply to just the province the cities are in, but to all Dwemer ruins around Tamriel? Being such a large place the people obviously have their differences (we see this when we compare the Dwemer of Skyrim to those of Vvardenfell) but the cities are similar, suggesting they shared ideas with each other at certain points. I guess this could be why all the Dwemer disapeared at once? I'm not suggesting we have a Blackreach the size of half of Tamriel (although that would be awesome), but a huge network of interconnected tunnels.

They all vanished at once because their entire race was a target of the hearts manipulation. If a group of Altmer who have lived in Black Marsh for thousands of years without interaction with the outside would use it in the exact same way, then the Altmer in Summerset would dissapear as well...

Highly unlikely. As already mentioned, Vvardenfell isn't really good terrain for that kind of thing, and such a tunnel system would require building under the inner sea, the illiac, mountains, lowlands, and maybe even a massive caldera. It would also take an absurd amount of work. It would be far too impractical, and not necessarily desired in the first place.

Also, it's worth noting that Morrowind seems to have been the heart and origin of Dwemer civilization, with the Dwemer flowing out from there. The Rourken, for example, abandoned their brethren in ancient Resdayn for Hammerfell.