The extra hit points for building military buildings in a city sounds pretty good. In theory, if you had military institutions there, you would have more resistance to attack.
Not sure about the 2nd attack part though. Doesn't really sound bad except for a couple of things. If you station, not garrison but just station, a ranged unit in the city you can get that second attack. If cities were able to get a second attack on their own, that could be 3 attacks just from the city hex in one turn. Granted cities are kind of easy to take down right now, but when you get one that's in a forest or something and it takes you 2 turns inside the cities bombard radius just to get to the city, that could be a minimum of 6 hits on a unit before it's ever even able to get to the city. You could have 9 hits on a unit before the unit gets off a second attack. And that only includes hits on one unit from the city hex. If you had any defensive units around your city as well, it could start to get real hard real quick to take a city. You would definitely need a bigger army, which is not necessarily a bad thing, but some of those units would just be cannon fodder I think.
