In large bowl, beat all icing ingredients except food colors with electric mixer on low speed until mixed. Beat on high speed 7 to 10 minutes or until very stiff. Divide and tint as desired with food colors. Decorate fronts of buildings as desired, using icing and assorted candies, nuts, cookies, crackers and cereal. Use icing to attach braces to backs of buildings. Let stand 30 minutes or until icing is completely set. Complete by decorating as desired.