City defenses feel rather weak overall. I have played with Ghandi and built up 70+ defenses only to see insta-healed riflemen breach their defenses with ease. I have taken a new city with my mech infy only to have the city fall the next turn to a beat up riflemen! So my suggestion is to help slow down rushes and to add more meaning to walls and castles is not only to nerf the insta-heals but to give the unit in garrison the ability to fight, as it would be if normally attacked, prior to the city falling. This unit, if infantry based, should also get a major defense bonus for it's urban terrain. So in theory, when the city in question reaches the point of collapse the city defenses cease to play a role and the defense is handed over to the unit garrisoned. This would slow down rushes, make defensive buildings a little more worthwhile and put importance on the units garrisoned. What do you think?