A Free City is a city which has left its original civilization due to a loss of Loyalty. These are not City-States, as they are likely to look towards rejoining one of the major civilizations of the game. A Free City has Loyalty to maintain just like a normal city, and accepts Loyalty pressure from other Civilizations. If its Loyalty reaches 0, it will join the Civilization that has exerted the most Loyalty pressure on it since the Free City became independent. This means there is a race against other civilizations when looking to attract a Free City into your civilization. Maximizing your Loyalty pressure will raise the chances that you will accumulate the most Loyalty and gain the city.
A Free City will repair pillaged improvements and spawn units to defend itself, and may build walls to defend itself. If attacked by a civilization, the Free City will try to retaliate against one of the civilization’s cities. Otherwise its citizens pursue their own activities, waiting to see which civilization of the world will be most attractive to them.