Concentration of bars and alcohol serving estabishments

An area is considered a Concentration of bars and alcohol serving estabishments if:
 * It is (relative to the alternatives) an attractive area to spend a night out and alcohol can be procured there
 * The number of alcohol serving and selling establishments per square meter is among the highest in the town/city
 * It is the only location where alcohol can be bought (at certain times of the day or night) for miles around