Cobb County Extension, 678 South Cobb Drive, Marietta. UGA Extension Cobb County invites the public to this free, family friendly event celebrating the opening of a unique outdoor classroom designed to inspire curiosity, connect people with nature, and bring research-based gardening education to life. Participate in hands-on activities, meet local conservation organizations, and join the Great Southeast Pollinator Census. Visitors of all ages are invited to explore the garden.