Tell your grandkids it’s a treat for them, not admitting you have childish yearnings for the sweet kingdom of Candytopia which runs from Sept.6 to Nov.30 next to the Marriot Marquis on Market Street. It’s another fantasia running amok, after color and ice cream exhibits in recent months, but this is a food art installation with paintings and room made out of confections, candy floss constructions, flying unicorn pigs, even a marshmallow tsunami and sugar laden treats being handed out throughout the day. Reservations only. Adults $34. Kids 4-12 $26.