Halloween Scavenger Hunt takes place on Saturday, Oct. 19, from 10 a.m. to noon. Children 10 years old and younger are invited to come in costume and pick up instructions from the starting location outside of the Museum on Main, 603 Main Street, Pleasantonl. Children will solve clues in order to find the next downtown location where they will be given a small goodie or treat. Participation will be limited to the first 600 children to arrive. Sponsored by Main Street Pediatric Dentistry & Orthodontics and Pacific Coast Farmers’ Market Association. Free.