Become a History Explorer! Engage in free hands-on activities and examine historical items up close with the San Diego History Center. Families welcome to drop in anytime between 11 a.m. – 2 p.m. Celebrate Earth Day Weekend with us! Learn about Kate Sessions, the “Mother of Balboa Park”, through free, hands-on activities, including decorating flower pots. A trailblazing horticulturist, Kate Sessions transformed San Diego’s landscape by introducing thousands of trees and plants — shaping the beauty of Balboa Park we love today. Your donation is your admission to our museums San Diego History Center on Facebook / Instagram