I would imagine that games based heavilly on cities would be based on principles from architecture, landscape and planning. It would seem to me that some of the best city environments are rich in landmarks and are easilly navigated. This enables the player to familiarise themselves with the environment quickly. Getting lost is a problem in both real-life cities as well as the virtual city (although there is usually a map in the menu system) but what else can contribute to the ease of navigation and the overall the beleivability of the environment?

I agree, although there is definately a distinction between games where the setting is an entire virtual city (eg GTA) and those which simply take place entirely in an urban environment (eg Left4Dead or even Mirror's Edge).

In the latter gameplay flow through the environment, atmosphere and aesthetics are more important than city planning aspects - players are less likely to be using architectural landmarks (in the traditional sense of the word) to navigate on a large scale ("go right near the smashed up car" rather than "it's near the Statue of Liberty", "lost :( ah! these buildings! looks like i'm in the financial district. my destination is east of here", "its on the edge of the suburbs").

ah interesting, this suggests that any objects in the game environment can become landmarks despite thier generic nature. The smashed up car in your example is easilly remembered and so helps with navigation of a level or area. I guess since the levels are always more or less the same architecturally (landscape and builings) this is made possible...