public City changeCityOwner(int cityID, Owner newOwner){
		int tmpX = cityMap.get(cityID).getXLocation();
		int tmpY = cityMap.get(cityID).getYLocation();
		this.removeID(cityID);
		City c = new City(cityID, tmpX, tmpY, newOwner);
		this.addVertex(c);
		return c;
	}