http://i121.photobucket.com/albums/o212/scottypma/imp.png

What are we looking at?

The city structures are actually in their own worldspace, and won't show up if you look at the IC in the Tamriel worldspace if that's what you're asking.

oh, ok thanks.

It's probably to stop the game lagging. The city's are loaded in a seperate section to the main map to stop the game running too slowly. If you jump over the walls to a city you will see what I mean.

that's the obvious reason,in morrowind the open world cities caused lag.