I've posted about this before in my review of .912, and it's happening again in 0.913. The AI has cities with 0 grain and 0 material, which only serves to drain their faction prestige. This time, it's a Tarth city, apparently a captured one from... Resoln? (not too sure). Maybe it's a bug in AI trying to raze each other cities? Just a stab in the dark.

The city is Caronsfell, right next to Procipinee in the save.

Screen: http://i107.photobucket.com/albums/m297/KStar099/Fallen%20Enchantress/FallenEnchantress_1336186949.jpg

Save: http://dl.dropbox.com/u/11827581/Pariden%20G1%20-%200%200%20City.zip

Edit:

Altar also had a similar city. Aegonford: http://i107.photobucket.com/albums/m297/KStar099/Fallen%20Enchantress/FallenEnchantress_1336188250.jpg

Same save, a bit northwest in FoW. Also a captured city.