The city of Vivec was awful. From an urban design perspective, it's as if they went out of their way to make the layout asinine. The very bridges between cantons, the entrances, and ramps between levels are evenly distributed in an effort to make them all as inconvenient as possible, which I suppose the slave owning populace wouldn't mind, but everyone else ought to. It wasn't an open city like most others in Morrowind, and the neighborhoods were so uncoordinated.
The windowless (mostly) mud ziggarat doesn't even strike the residents as a suffocation risk with the indoor torches burning away the oxygen, but without those for light the whole indoor area should be a damp, moldy, and dirty structure with all the people maintaining a permanent cough. And there's a sewer on this thing? It's built out on the water, there's no storm sewer since the water runs down the outside, there's no processing of the wasted dropped into the non-existent toilets, so is there any reason whatsoever that this strange cluster[censored] of a place has a sewer system? It just drops it into the inlet anyway, and there's no running water.
Imperial City. Ugly, deserted, a lame excuse of a capital.
For me it was the Imperial City. I felt the Imperial City was too barren and lifeless. It lacked the illusion of a real city for me. I could not suspend my disbelief. On top of everything else its nearly identical pie-shaped districts were a pain to traverse.
I agree that the Imperial City was pretty bad. It actually had the opposite design philosophy that the center of power of an empire should have. Centers of power need to be crazy unorganized messes, where new emperors tear down things as they choose and build other things. Where poor people crowd up all the square footage they can and have a complicated relationship with the power structure. The city didn't even have a mayor, are they expecting the damn emperor to run their city? He has bigger things to take care of! The Imperial Palace barely had anything to it, and there weren't apartments built for the visiting kings, diplomats, and dignitaries. Or even the Elder Council!