I saw a panorama painting of Jerusalem ad.40 in a historic magazine recently.
I can't show you the real pic, but this is something close enough to give you an idea.
Oh, yes, I am going to make this baby.
You think it's unplayable ?

So far I've done 10-20% of the whole map...
Should I get some medication or finish the job ?




This is going to such a big a** map...
(of course i add proper distance culling and fog to make it playable, I'm not THAT CRAZY...!)

If you plan on making it like that it would be too big, try making a smaller playble vertion of it that would be more interesting.

well if your going to make it that big, add plenty of jeeps. or is this even a cod map?

oh nvm it's SoFII

The buildings would probably not be an issue. I would scale it down to about half. If you notice the stone walls surrounding the city. On the tops of these walls is where the problem will raise it's ugly head. All the little blocks on top of the walls will generate an error which is very hard to get rid of. When I built redrum's keep the major issues were the tops of the walls and stairs.
Check out this thread:

Walls and Errors

if its so large that you cant easily find other people then i wouldnt consider it playable.

i always say big is beautiful, but then my friends mock me for dating fat chicks

but back to the map, the problem with making a really big map is that most people will not want to play it. so you have to decide if it is worth spending all that time and effort in making it for the end result to be left unplayed.
it would be like that map based on the prisoner that was released a while back. it looked amazing, but the only time i saw it in game it was in empty servers.