The whole city in 10mm??? 
Nah, it'd be too big. Going on info gleaned from various websites, the city would be just over six metres wide and about 1.3m tall to the top of the seventh level (approx 1:160 for 10mm).
So, a section that goes on the table edge showing the spur and a couple of levels but mainly the table would show the homesteads and fields etc in the Pelennor

I also forgot about the Ted Nasmith version, which apart from the lack of a black wall is quite a good one

There is also a Japanese version someone has done for Shogun Total war


edit: so any estimations or exact numbers even about the population of Minas T in any of the sources?
The only reference to population I've found (and it's only a cursory look) is 50,000 which to my mind is too many

(I'm not helping, am I?
)
I don't need any help in going overboard with projects

Hobbits is 28mm

cheers
James