The maximum number of occupiable cities will be decided based on Guild Level.

And, Occupation Points Needed are also different according to the size of cites. Wthin City Occupation Points, you can own up to 3 cities regardiess of the kind of cities(.Metropolis, Mid-sized City, Town) except World Tower.

Required points for each city size are like below.

 - Metropolis: 150 Points

 - Mid-sized City: 100 Points

 - Town: 50 Points

However, World Tower is not counted to the number of occupiable cities, and also not counted to Occupation Points.