Two problems and accompanying suggestions:
1) Currently, when a city is razed the tiles that initially supported the settlement of a city (representing good soil, presence of minerals, magic, etc...) are removed from the map. This doesn't make much logical sense, and doesn't really do much to advance the gameplay either. These sites are already in somewhat short supply. I would suggest leaving the underlying tiles untouched. While some environmental degradation would be understandable, as it is now the only way to make sense of the mechanic is to imagine that the cave bear who got in some lucky mauls and tore down my town then proceeded to salt the earth and taint all of the minerals in the area. A pretty comprehensive force of destruction...
2) Speaking of cave bears, or ophidians for that matter, currently the situation is thus: a large monster army manages to wipe out my town garrison in a closely fought battle, leaving perhaps one monster with low health left. Result: a city of 150 is razed to the ground (and the earth salted, see point 1). Again, doesn't make much sense logically and is somewhat frustrating. A more sensible mechanic would be for the surviving attack power of the monster stack to be subtracted from the population of the city, and if this resulted in a population of zero, then the city would be razed.
Thoughts?