How can i build a city as a bunker ?

I want to add the possibility of build a city everywhere on the map as a bunker in wc3

Anyone know how to do this ?

I have seen a function in armysettings.json

{"AirborneId":0,"AOEin1":0,"AOEin2":0,"Army":20,"CD":0,"CostMoney":0,"CostOil":0,"CostSteel":0,"Defence":0,"Feature":[],"HP":200,"Id":104401,"Level":1,"MaxAttack":0,"MaxRange":0,"MinAttack":0,"MinRange":0,"Mobility":0,"MoveOil":0,"Name":"City","OName":"小城市","shield":0,"Type":6,"UpgradeId":0},{"AirborneId":0,"AOEin1":0,"AOEin2":0,"Army":20,"CD":0,"CostMoney":0,"CostOil":0,"CostSteel":0,"Defence":0,"Feature":[],"HP":400,"Id":104402,"Level":2,"MaxAttack":0,"MaxRange":0,"MinAttack":0,"MinRange":0,"Mobility":0,"MoveOil":0,"Name":"City","OName":"中小城市","shield":0,"Type":6,"UpgradeId":0