What is the religious ruling on preparing bars and places where prohibited items, such as alcoholic beverages and the like, are served?

It is not permissible to furnish places where alcoholic beverages are consumed, nor to assist in furnishing them, for that entails cooperation in sin and aggression. Allah Almighty said: "And cooperate in righteousness and piety, but do not cooperate in sin and aggression." And drinking alcohol is one of the major sins.