Some ruins are ancient cities, but I see no reason to assume that all are--or will be.

FO3 was much better than OB in making dungeons seem lived-in (currently, like raider hideouts, or previously, like vaults, and often both). Hopefully some of that carries over to Skyrim.
I thought the ancestral tombs in MW were particularly well-done - you could tell people had been there leaving offerings, made you feel like more of an intruder.

The interior of the Ayleid ruins, the layout, always reminded me of a fortification or stronghold.

A long, windy and hazardous way to a central location, and an easy way from there back to the entrance.
Usually on a high ledge, handy for arrows or boiling oil.

The living quarters of the city would have been above ground, and now mostly completely destroyed.

It always seemed to me that the dungeons looked designed on the one hand keep slaves in, and on the other to keep invaders out.

I agree

I suppose I never thought of it that way, and that does make sense. Though the above ground portions never gave me that impression but I suppose it would work that way.

Still, would like to see the interiors telling a story specific to that location. Keeping my fingers crossed on that.

The the dungeons in Oblivion were lackluster at best. There was one every 4 feet. You couldn't swing a cat without hitting one. They weren't secret, they weren't dangerous (thanks level scaling) there was no joy in finding them (thanks compass) and they all looked almost exactly the same. I had no idea those elven dungeons were supposed to be CITIES. They look nothing like cities. They seem more like churches than cities.

I guess some aren't the equivalent of cities but more like forts, which explains the more battle-oriented nature of them. Good catch though.

This makes a lot of sense-- thanks!

I always thought of the ruins as the remains of the catacombs, ancient graves where one would expect to find traps and ghosts and such. The forts were both graves and dungeons/jail as evidenced by the names you could sometimes see entering the lower levels. Back to the Ayleid ruins, aboveground the remains almost always formed a circular plan, maybe they were the worship centers or the keep? Both of those are generally made of stone where normal housing is wood and daub and thatch, stuff that would rot away over time.

Ever been to a ruin in our own world? They're confusing jumbles of rock and it can be difficult to identify the purpose of one area from another, unless you're a trained proffessional.

If there are 2 things from FO3 that I could pick to see in Skyrim, it's the improved level scaling and the more realistically designed 'dungeons' of FO3. Springvale school, Super Duper Market, Shalebridge tunnels, Dunwich building, the vaults... All very memorable.

its a video game, its not gonna be a city because it is designed to be a closed area that you can only go 1 or a few paths in, you cannot do that in a city, they did do this with merhrunes razor which worked quite well but they still went back to it being shaped like a level

Indeed. You can tell by the preponderance of slots carved into the walls and body slabs. These were cities for the dead, not the living; whereas the exteriors of places such as Fanacasecul felt like it could have been prime water-front property at one point in it's history.

Forts on the other hand, were an utter disappointment. I mean, how the does the legion even maintain the scantest presence in Cyrodiil when they only have one small stronghold in the entire province (by which I mean the IC prison/bastion, of course).